Journal articles: 'Cetacea, Fossil'

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O'Leary, Maureen A., and Mark D. Uhen. "The time of origin of whales and the role of behavioral changes in the terrestrial-aquatic transition." Paleobiology 25, no. 4 (1999): 534–56. http://dx.doi.org/10.1017/s0094837300020376.

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Addition of the recently discovered fossil Nalacetus to a phylogenetic analysis of basicranial, cranial, dental, postcranial, and soft morphological characters reveals that it is the most basal cetacean, and that mesonychians form the monophyletic sister group to Cetacea. The molars of Nalacetus elucidate transformations in dental morphology that occurred early in the cetacean radiation and clarify certain derived differences in molar cusp position between cetaceans and the extinct clade, Mesonychia, hypothesized to be their sister taxon. Nalacetus and other archaic cetaceans share derived vertically elongate shearing facets on the lower molars. Applying the Extant Phylogenetic Bracket, we advance the hypothesis that these facets are an osteological correlate of aquatic predation. Our functional interpretation of this character and its distribution within Cetacea indicates that a behavioral change in tooth use characterized the origin of the clade. Comparison of the transformation of this dental character with that of the cetacean pelvis indicates that a change in tooth use (feeding behavior) occurred before loss of the ability to engage in terrestrial locomotion.The most parsimonious phylogenetic hypothesis presented here has a significant fit with the stratigraphic record as determined by the Manhattan Stratigraphic Measure, which is corroborated by retention indices of stratigraphic data. Ghost lineages necessitated by the phylogenetic hypothesis extend the stratigraphic range of Cetacea into the middle Paleocene (Torrejonian), ten million years earlier than the oldest cetacean fossil currently known. Primitive features of Nalacetus, the large number of synapomorphies diagnosing Cetacea, and the implied ghost lineage suggest that the early cetacean radiation was much more extensive than has been previously recognized.

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Loch, Carolina, Jules A. Kieser, and R. Ewan Fordyce. "Enamel Ultrastructure in Fossil Cetaceans (Cetacea: Archaeoceti and Odontoceti)." PLOS ONE 10, no. 1 (January 28, 2015): e0116557. http://dx.doi.org/10.1371/journal.pone.0116557.

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Bianucci, Giovanni, Christian de Muizon, Mario Urbina, and Olivier Lambert. "Extensive Diversity and Disparity of the Early Miocene Platanistoids (Cetacea, Odontoceti) in the Southeastern Pacific (Chilcatay Formation, Peru)." Life 10, no. 3 (March 18, 2020): 27. http://dx.doi.org/10.3390/life10030027.

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Several aspects of the fascinating evolutionary history of toothed and baleen whales (Cetacea) are still to be clarified due to the fragmentation and discontinuity (in space and time) of the fossil record. Here we open a window on the past, describing a part of the extraordinary cetacean fossil assemblage deposited in a restricted interval of time (19–18 Ma) in the Chilcatay Formation (Peru). All the fossils here examined belong to the Platanistoidea clade as here redefined, a toothed whale group nowadays represented only by the Asian river dolphin Platanista gangetica. Two new genera and species, the hyper-longirostrine Ensidelphis riveroi and the squalodelphinid Furcacetus flexirostrum, are described together with new material referred to the squalodelphinid Notocetus vanbenedeni and fragmentary remains showing affinities with the platanistid Araeodelphis. Our cladistic analysis defines the new clade Platanidelphidi, sister-group to Allodelphinidae and including E. riveroi and the clade Squalodelphinidae + Platanistidae. The fossils here examined further confirm the high diversity and disparity of platanistoids during the early Miocene. Finally, morphofunctional considerations on the entire platanistoid assemblage of the Chilcatay Formation suggest a high trophic partitioning of this peculiar cetacean paleocommunity.

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Aguirre-Fernández, Gabriel, Jorge D. Carrillo-Briceño, Rodolfo Sánchez, Eli Amson, and Marcelo R. Sánchez-Villagra. "Fossil Cetaceans (Mammalia, Cetacea) from the Neogene of Colombia and Venezuela." Journal of Mammalian Evolution 24, no. 1 (August 31, 2016): 71–90. http://dx.doi.org/10.1007/s10914-016-9353-x.

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RAVIKANT, VADLAMANI, and S. BAJPAI. "Strontium isotope evidence for the age of Eocene fossil whales of Kutch, western India." Geological Magazine 147, no. 3 (February 8, 2010): 473–77. http://dx.doi.org/10.1017/s0016756810000099.

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AbstractThe Indian subcontinent is widely considered to be the birthplace of whales (Cetacea), and the middle Eocene Harudi Formation of Kutch has long been known to be a major source of early whales. The Kutch cetaceans are of critical importance in understanding the evolutionary transition of whales from land to sea. Strontium isotope analysis of marine biogenic carbonates from the Harudi Formation was conducted to obtain a numerical age of the whale-bearing strata. Although the measured 87Sr/86Sr ratios (0.707742 to 0.707764) correspond to two distinct age clusters of 46–47.5 Ma or 41–42.5 Ma, we prefer the latter, late Lutetian, age cluster.

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Etienne, Rampal S., Bart Haegeman, Tanja Stadler, Tracy Aze, Paul N. Pearson, Andy Purvis, and Albert B. Phillimore. "Diversity-dependence brings molecular phylogenies closer to agreement with the fossil record." Proceedings of the Royal Society B: Biological Sciences 279, no. 1732 (October 12, 2011): 1300–1309. http://dx.doi.org/10.1098/rspb.2011.1439.

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The branching times of molecular phylogenies allow us to infer speciation and extinction dynamics even when fossils are absent. Troublingly, phylogenetic approaches usually return estimates of zero extinction, conflicting with fossil evidence. Phylogenies and fossils do agree, however, that there are often limits to diversity. Here, we present a general approach to evaluate the likelihood of a phylogeny under a model that accommodates diversity-dependence and extinction. We find, by likelihood maximization, that extinction is estimated most precisely if the rate of increase in the number of lineages in the phylogeny saturates towards the present or first decreases and then increases. We demonstrate the utility and limits of our approach by applying it to the phylogenies for two cases where a fossil record exists (Cetacea and Cenozoic macroperforate planktonic foraminifera) and to three radiations lacking fossil evidence ( Dendroica , Plethodon and Heliconius ). We propose that the diversity-dependence model with extinction be used as the standard model for macro-evolutionary dynamics because of its biological realism and flexibility.

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Fitzgerald, Erich M. G. "A review of the Tertiary fossil Cetacea (Mammalia) localities in Australia." Memoirs of Museum Victoria 61, no. 2 (2004): 183–208. http://dx.doi.org/10.24199/j.mmv.2004.61.12.

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O'Leary, Maureen A., Biren A. Patel, and Mark N. Coleman. "Endocranial petrosal anatomy of Bothriogenys (Mammalia, Artiodactyla, Anthracotheriidae), and petrosal volume and density comparisons among aquatic and terrestrial artiodactyls and outgroups." Journal of Paleontology 86, no. 1 (January 2012): 44–50. http://dx.doi.org/10.1666/10-091.1.

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We provide the first detailed endocranial description of the petrosal bone of the ear region of the anthracotheriid artiodactyl Bothriogenys, based on two new specimens from the early Oligocene of the Jebel Qatrani Formation, Fayum, Egypt. The new fossils have petrosals with a hyperinflated (pachyostotic) tegmen tympani (the roof over the middle ear), resembling the condition in certain cetancodontans such as hippopotamids and basal cetaceamorphans (fossil stem taxa to extant Cetacea).The morphology of the petrosal, particularly its relative size and density, has been considered an important indicator of the ability of a marine mammal to localize sound transmitted in water, yet petrosal size (pachyostosis) and density (osteosclerosis) have not previously been quantified independent of each other. We examine the new fossils in the context of a preliminary CT-based study of petrosal density (extant taxa only) and petrosal volume (extant and extinct taxa) in a sample of artiodactyls and outgroups. In our extant comparative sample, the petrosals of cetaceans are both dense and voluminous as has been previously stated. We find, however, that the tegmen tympani is relatively voluminous (pachyostotic) without being particularly dense (osteosclerotic) in Hippopotamus amphibius, an extant taxon that has been documented to show some aquatic hearing behaviors, albeit less derived ones than those seen in cetaceans. A voluminous tegmen tympani, which is present in Bothriogenys, may have specific implications for behavior that are distinct from increases in petrosal density.

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Buchholtz, Emily A. "Vertebral osteology and swimming style in living and fossil whales (Order: Cetacea)." Journal of Zoology 253, no. 2 (February 2001): 175–90. http://dx.doi.org/10.1017/s0952836901000164.

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Tsai, Cheng-Hsiu, and Robert W. Boessenecker. "An Early Pleistocene gray whale (Cetacea: Eschrichtiidae) from the Rio Dell Formation of northern California." Journal of Paleontology 89, no. 1 (January 2015): 103–9. http://dx.doi.org/10.1017/jpa.2014.9.

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AbstractThe earliest fossil gray whale (Eschrichtius) from the eastern North Pacific is reported from the Lower Pleistocene Rio Dell Formation of Humboldt County, Northern California. This specimen, a tympanic bulla and posterior process, is identical in morphology to extantEschrichtius robustusand differs from PlioceneEschrichtiussp. from the western North Pacific (Japan). Thus, it suggests that the modern bulla morphology of the gray whale had been acquired by the Early Pleistocene. The absence of fossilEschrichtiusin the Pliocene of the eastern North Pacific may indicate that the extant gray whale lineage originated in the western North Pacific during the Pliocene before invading the eastern North Pacific during the Early Pleistocene. Further discoveries of Plio-Pleistocene gray whale fossils will help test this hypothesis and properly interpret the evolutionary history of eschrichtiid clade.

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Bosio, Giulia, Alberto Collareta, Claudio Di Celma, Olivier Lambert, Felix G. Marx, Christian de Muizon, Anna Gioncada, et al. "Taphonomy of marine vertebrates of the Pisco Formation (Miocene, Peru): Insights into the origin of an outstanding Fossil-Lagerstätte." PLOS ONE 16, no. 7 (July 15, 2021): e0254395. http://dx.doi.org/10.1371/journal.pone.0254395.

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The Miocene Pisco Formation, broadly exposed in the Ica Desert of southern Peru, is among the most outstanding Cenozoic marine Fossil-Lagerstätten worldwide. It is renowned for its exceptional preservation and abundance of vertebrate fossils, including a rich assemblage of whales and dolphins (Cetacea). Here, we integrate taphonomic data on 890 marine vertebrate fossils, gathered through 16 different localities. Our observations range from the taxonomic distribution, articulation, completeness, disposition and orientation of skeletons, to the presence of bite marks, associations with shark teeth and macro-invertebrates, bone and soft tissue preservation, and the formation of attendant carbonate concretions and sedimentary structures. We propose that the exceptional preservation characterising many Pisco vertebrates, as well as their exceptionally high abundance, cannot be ascribed to a single cause like high sedimentation rates (as proposed in the past), but rather to the interplay of several favourable factors including: (i) low levels of dissolved oxygen at the seafloor (with the intervention of seasonal anoxic events); (ii) the early onset of mineralisation processes like apatite dissolution/recrystallisation and carbonate mineral precipitation; (iii) rapid burial of carcasses in a soupy substrate and/or a novel mechanism involving scour-induced self-burial; and (iv) original biological richness. Collectively, our observations provide a comprehensive overview of the taphonomic processes that shaped one of South America’s most important fossil deposits, and suggest a model for the formation of other marine vertebrate Fossil-Lagerstätten.

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Fordyce, R. Ewan, Patrick G. Quilty, and James Daniels. "Australodelphis mirus, a bizarre new toothless ziphiid-like fossil dolphin (Cetacea: Delphinidae) from the Pliocene of Vestfold Hills, East Antarctica." Antarctic Science 14, no. 1 (March 2002): 37–54. http://dx.doi.org/10.1017/s0954102002000561.

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Australodelphis mirus (Delphinidae n. gen., n. sp) is a small extinct Early Pliocene dolphin known from five individuals from shallow-water strata of the Sørsdal Formation, Vestfold Hills, East Antarctica. Australodelphis mirus is the first higher vertebrate named from the Oligocene-Pleistocene interval on land in Antarctica, and is the first cetacean fossil from the polar margin of circum-Antarctic Southern Ocean that postdates the break-up of Gondwana. The dolphin is convergent in skull form with some living beaked whales (Mesoplodon spp.; Family Ziphiidae) in its long, narrow and toothless upper jaw and face, but skull suture patterns, basicranial sinuses, and ear-bones indicate close relationship with living long-beaked dolphins (Delphinidae). Australodelphis mirus perhaps was a suction-feeding squid-eater which occupied quiet near-shore shelf waters influenced by glaciers but probably lacking major sea-ice. Possible ecological equivalents of A. mirus (small ziphiids, long-beaked dolphins) do not occupy Antarctic waters today, perhaps excluded by cold conditions and/or sea-ice cover. Earlier Pliocene cetaceans worldwide reveal significant extinct and sometimes bizarre taxa, and extant families with ranges quite different from today, pointing to climate-related changes in cetacean ecology in the last 2–3 million years.

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Bisconti, Michelangelo, Luca Pellegrino, and Giorgio Carnevale. "Evolution of gigantism in right and bowhead whales (Cetacea: Mysticeti: Balaenidae)." Biological Journal of the Linnean Society 134, no. 2 (July 18, 2021): 498–524. http://dx.doi.org/10.1093/biolinnean/blab086.

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Abstract The evolution of gigantic body size represents a key to understand the ecological role of baleen whales in oceanic ecosystems. Many efforts have been devoted to the formulation of equations relating different body parts to total body length and mass in living and fossil mysticetes, mainly focusing on balaenopterid and balaenopterid-like mysticetes. Right whales (family Balaenidae) have a unique head-to-body length ratio, suggesting that their body proportions cannot be predicted effectively using equations based primarily on non-balaenid mysticetes. A new morphometric dataset of living and fossil balaenids is provided herein, and new regression equations allow one to predict the body length and mass of extinct species based on the expected head-to-body length ratio of extant balaenids. The reconstructed values are mapped on a new phylogenetic analysis of the Balaenidae, inferring body size and mass at ancestral nodes. The variations of body size and mass in Balaenidae since the early Miocene are reconstructed, revealing that: (1) a reduction in total body length occurred in the early Pliocene; (2) the origin of the gigantic body size in the bowhead whale (Balaena mysticetus) is probably related to invasion of the Arctic Ocean in the last 3 Myr; and (3) the origin of the gigantic body size in the right whales (genus Eubalaena) occurred since the latest Miocene, probably concomitant with pulses of nutrients sustaining large zooplankton populations. We suggest that the evolution of gigantism in Balaenidae occurred independently in two lineages and, probably, in response to different palaeoenvironmental drivers.

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Fitzgerald, Erich M. G. "A fossil sperm whale (Cetacea, Physeteroidea) from the Pleistocene of Nauru, equatorial southwest Pacific." Journal of Vertebrate Paleontology 31, no. 4 (July 2011): 929–31. http://dx.doi.org/10.1080/02724634.2011.579670.

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Uhen, Mark D., and David Taylor. "A basilosaurid archaeocete (Cetacea, Pelagiceti) from the Late Eocene of Oregon, USA." PeerJ 8 (October 2, 2020): e9809. http://dx.doi.org/10.7717/peerj.9809.

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Background Basilosaurid archaeocetes are known from the Late Eocene of virtually all coastlines bearing coeval marine rocks except the North Pacific Basin, until now. Here we report on three consecutive posterior thoracic vertebrae of a large, basilosaurid archaeocete from a Late Eocene horizon in the Keasey Formation in Oregon. Methods These vertebrae were morphologically and morphometrically compared to other vertebrae of similar age from around the world. Results The specimens were determined to be different from all currently named species of fossil cetacean, but most similar to those found in the Gulf Coast region of North America. These vertebrae represent the first confirmed specimen of a Late Eocene basilosaurid from the North Pacific. These and other basilosaurids known only from vertebrae are reviewed here in the context of Late Eocene paleoceanography and cetacean evolution.

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Ichishima, Hiroto, and Masaichi Kimura. "A new fossil porpoise (Cetacea; Delphinoidea; Phocoenidae) from the Early Pliocene Horokaoshirarika Formation, Hokkaido, Japan." Journal of Vertebrate Paleontology 20, no. 3 (September 25, 2000): 561–76. http://dx.doi.org/10.1671/0272-4634(2000)020[0561:anfpcd]2.0.co;2.

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Tanaka, Yoshihiro, Hitoshi Furusawa, and Masaichi Kimura. "A new member of fossil balaenid (Mysticeti, Cetacea) from the early Pliocene of Hokkaido, Japan." Royal Society Open Science 7, no. 4 (April 2020): 192182. http://dx.doi.org/10.1098/rsos.192182.

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The family Balaenidae includes two genus and four extant species. Extinct balaenids are known for at least four genus and 10 species. The oldest known record of members of the Balaenidae is known from the early Miocene, but still need more early members of the family to provide better phylogenetic hypotheses. FCCP 1049 from the lower part of the Chippubetsu Formation, Fukagawa Group (3.5–5.2 Ma, Zanclean, early Pliocene) was preliminary described and identified as Balaenula sp. by Furusawa and Kimura in 1982. Later works discussed that FCCP 1049 is different from the genus, and is placed in different clade from Balaenula astensis . The result of our phylogenetic analysis places FCCP 1049 basal to Balaenella brachyrhynus , and is again separated from B. astensis. In this study, FCCP 1049 is re-described and named as Archaeobalaena dosanko gen. et sp. nov. Archaeobalaena dosanko is distinguishable from other balaenids by having a deep promontorial groove of the pars cochlearis of the periotic. Archaeobalaena dosanko can be differentiated from other balaenids, except Morenocetus parvus by having a slender zygomatic process, and posteriorly oriented postorbital process in dorsal view. Archaeobalaena dosanko adds detailed skull, periotic and bulla morphologies for the earlier balaenids.

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Ichishima, Hiroto. "A new fossil kentriodontid dolphin (Cetacea; Kentriodontidae) from the Middle Miocene Takinoue Formation, Hokkaido, Japan." Island Arc 3, no. 4 (December 1994): 473–85. http://dx.doi.org/10.1111/j.1440-1738.1994.tb00126.x.

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Post, Klaas, Stephen Louwye, and Olivier Lambert. "Scaldiporia vandokkumi, a new pontoporiid (Mammalia, Cetacea, Odontoceti) from the Late Miocene to earliest Pliocene of the Westerschelde estuary (The Netherlands)." PeerJ 5 (November 1, 2017): e3991. http://dx.doi.org/10.7717/peerj.3991.

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Background The family Pontoporiidae (Cetacea, Odontoceti, Inioidea) is currently represented in our oceans by just one species of diminutive dolphin (Pontoporia blainvillei, franciscana). Although P. blainvillei is limited to coastal waters of the South Atlantic along Brazil, Uruguay and Argentina, multiple Miocene and Pliocene fossils indicate the past presence of members of the family in the South Atlantic, South Paciifc and North Atlantic oceans. Our comprehension of the origin and diversity of this clade and of the relationships of its members with other inioids is hampered by the fact that part of the described fossil specimens, especially from the North Atlantic realm, are cranial fragments often associated to limited stratigraphic information. Methods Based on an almost complete fossil cranium of pontoporiid from the Westerschelde estuary, The Netherlands, whose preservation allows for detailed morphological observations, we describe a new genus and species. The latter is compared to other pontoporiids, as well as a few non-pontoporiid inioids. A phylogenetic analysis is performed to investigate the relationship of S. vandokkumi with the best-known extinct and extant inioids. Palynological analysis of the sediment associated to the holotype is used to assess its geological age. Results and discussion The new genus and species Scaldiporia vandokkumi is characterized among others by greatly thickened premaxillary eminences reaching the level of the antorbital notch. Palynologically dated from the late Tortonian—earliest Zanclean (7.6–5 Ma, Late Miocene—earliest Pliocene), this new pontoporiid confirms the surprising past diversity of marine inioids in the North Atlantic area. Finally the content of the pontoporiid subfamily Brachydelphininae is briefly discussed.

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Leslie, Matthew S., Carlos Mauricio Peredo, and Nicholas D. Pyenson. "Norrisanima miocaena, a new generic name and redescription of a stem balaenopteroid mysticete (Mammalia, Cetacea) from the Miocene of California." PeerJ 7 (October 8, 2019): e7629. http://dx.doi.org/10.7717/peerj.7629.

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Rorqual whales are among the most species rich group of baleen whales (or mysticetes) alive today, yet the monophyly of the traditional grouping (i.e., Balaenopteridae) remains unclear. Additionally, many fossil mysticetes putatively assigned to either Balaenopteridae or Balaenopteroidea may actually belong to stem lineages, although many of these fossil taxa suffer from inadequate descriptions of fragmentary skeletal material. Here we provide a redescription of the holotype of Megaptera miocaena, a fossil balaenopteroid from the Monterey Formation of California, which consists of a partial cranium, a fragment of the rostrum, a single vertebra, and both tympanoperiotics. Kellogg (1922) assigned the type specimen to the genus Megaptera Gray (1846), on the basis of its broad similarities to distinctive traits in the cranium of extant humpback whales (Megaptera novaeangliae (Borowski, 1781)). Subsequent phylogenetic analyses have found these two species as sister taxa in morphological datasets alone; the most recent systematic analyses using both molecular and morphological data sets place Megaptera miocaena as a stem balaenopteroid unrelated to humpback whales. Here, we redescribe the type specimen of Megaptera miocaena in the context of other fossil balaenopteroids discovered nearly a century since Kellogg’s original description and provide a morphological basis for discriminating it from Megaptera novaeangliae. We also provide a new generic name and recombine the taxon as Norrisanima miocaena, gen. nov., to reflect its phylogenetic position outside of crown Balaenopteroidea, unrelated to extant Megaptera. Lastly, we refine the stratigraphic age of Norrisanima miocaena, based on associated microfossils to a Tortonian age (7.6–7.3 Ma), which carries implications for understanding the origin of key features associated with feeding and body size evolution in this group of whales.

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Tsai, Cheng-Hsiu, and R. Ewan Fordyce. "Ancestor–descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata." Biology Letters 11, no. 1 (January 2015): 20140875. http://dx.doi.org/10.1098/rsbl.2014.0875.

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Ancestor–descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra , and its sole living relative, the enigmatic pygmy right whale Caperea marginata , the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR—the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea–Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium.

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Boersma, Alexandra T., and Nicholas D. Pyenson. "Arktocara yakataga, a new fossil odontocete (Mammalia, Cetacea) from the Oligocene of Alaska and the antiquity of Platanistoidea." PeerJ 4 (August 16, 2016): e2321. http://dx.doi.org/10.7717/peerj.2321.

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The diversification of crown cetacean lineages (i.e., crown Odontoceti and crown Mysticeti) occurred throughout the Oligocene, but it remains an ongoing challenge to resolve the phylogenetic pattern of their origins, especially with respect to stem lineages. One extant monotypic lineage,Platanista gangetica(the Ganges and Indus river dolphin), is the sole surviving member of the broader group Platanistoidea, with many fossil relatives that range from Oligocene to Miocene in age. Curiously, the highly threatenedPlatanistais restricted today to freshwater river systems of South Asia, yet nearly all fossil platanistoids are known globally from marine rocks, suggesting a marine ancestry for this group. In recent years, studies on the phylogenetic relationships in Platanistoidea have reached a general consensus about the membership of different sub-clades and putative extinct groups, although the position of some platanistoid groups (e.g., Waipatiidae) has been contested. Here we describe a new genus and species of fossil platanistoid,Arktocara yakataga, gen. et sp. nov. from the Oligocene of Alaska, USA. The type and only known specimen was collected from the marine Poul Creek Formation, a unit known to include Oligocene strata, exposed in the Yakutat City and Borough of Southeast Alaska. In our phylogenetic analysis of stem and node-based Platanistoidea,Arktocarafalls within the node-based sub-clade Allodelphinidae as the sister taxon toAllodelphis pratti. With a geochronologic age between ∼29–24 million years old,Arktocarais among the oldest crown Odontoceti, reinforcing the long-standing view that the diversification for crown lineages must have occurred no later than the early Oligocene.

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Bisconti, Michelangelo, and Mark E. J. Bosselaers. "A new balaenopterid species from the Southern North Sea Basin informs about phylogeny and taxonomy of Burtinopsis and Protororqualus (Cetacea, Mysticeti, Balaenopteridae)." PeerJ 8 (August 12, 2020): e9570. http://dx.doi.org/10.7717/peerj.9570.

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Background An extensive radiation can be inferred among balaenopterid mysticetes in the last 10 million years based on a rich fossil record. Many extinct genera and species have been established in the past by the study of fossil rorquals from northern and southern hemispheres. In many cases, the new fossils are used to create new genera. However, in very recent times, new species of known genera have been described that help our understanding of the speciation processes and the biogeography of these whales. Here, a new species of balaenopterid whales is described in order to better understand the past diversity of Balaenopteridae and to analyze its paleobiogeographical implications. As the new species closely resembles a taxon established in the 19th century (i.e., Burtinopsis), a detailed analysis of this taxon was necessary to support the new taxonomic statements of this article. Methods A new partial skeleton including skull and earbones is described and compared to an extended sample of living and fossil mysticete species. A phylogenetic analysis including 355 character states scored in 88 taxa was performed to understand its relationships within the genus Protororqualus, to allow paleobiogeographic inferences and to better understand the relationships of Protororqualus within Balaenopteridae. Maximum parsimony analyses of character evolution were performed to understand morphological transformations within Balaenopteridae. The revision of Burtinopsis was carried out based on detailed descriptions and comparisons of the type materials that were figured and measured. Results Protororqualus wilfriedneesi sp. nov. was established based on a comparative analysis of the skull and earbone morphology. The specimen is dated back to the Zanclean (Lower Pliocene, between c. 5.3 and 3.6 Ma). A taphonomical study of the holotype skeleton revealed evidence of interactions with sharks and fishes before the definitive burial of the carcass. Based on the phylogenetic analysis, the monophyly of the genus Protororqualus was confirmed. Protororqualus wilfriedneesi sp. nov. was more derived than Protororqualus cuvieri suggesting that it resulted from an invasion of the North Sea Basin (and the North Atlantic ocean) from the Mediterranean basin. Several specimens from western and eastern sides of the Atlantic Ocean are described that suggest that Protororqualus wilfriedneesi had a trans-Atlantic distribution in the Pliocene.

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Lloyd, Graeme T., and Graham J. Slater. "A Total-Group Phylogenetic Metatree for Cetacea and the Importance of Fossil Data in Diversification Analyses." Systematic Biology 70, no. 5 (January 28, 2021): 922–39. http://dx.doi.org/10.1093/sysbio/syab002.

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Abstract Phylogenetic trees provide a powerful framework for testing macroevolutionary hypotheses, but it is becoming increasingly apparent that inferences derived from extant species alone can be highly misleading. Trees incorporating living and extinct taxa are needed to address fundamental questions about the origins of diversity and disparity but it has proved challenging to generate robust, species-rich phylogenies that include large numbers of fossil taxa. As a result, most studies of diversification dynamics continue to rely on molecular phylogenies. Here, we extend and apply a recently developed meta-analytic approach for synthesizing previously published phylogenetic studies to infer a well-resolved set of species level, time-scaled phylogenetic hypotheses for extinct and extant cetaceans (whales, dolphins, and allies). Our trees extend sampling from the $\sim 90$ extant species to over 500 living and extinct species, and therefore allow for more robust inference of macroevolutionary dynamics. While the diversification scenarios, we recover are broadly concordant with those inferred from molecular phylogenies they differ in critical ways, notably in the relative contributions of extinction and speciation rate shifts in driving rapid radiations. The metatree approach provides the most immediate route for generating higher level phylogenies of extinct taxa and opens the door to re-evaluation of macroevolutionary hypotheses derived only from extant taxa.[Extinction; macroevolution; matrix representation with parsimony; morphology; supertree.]

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Bianucci, Giovanni, Giulia Bosio, Elisa Malinverno, Christian de Muizon, Igor M. Villa, Mario Urbina, and Olivier Lambert. "A new large squalodelphinid (Cetacea, Odontoceti) from Peru sheds light on the Early Miocene platanistoid disparity and ecology." Royal Society Open Science 5, no. 4 (April 2018): 172302. http://dx.doi.org/10.1098/rsos.172302.

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The South Asian river dolphin ( Platanista gangetica ) is the only extant survivor of the large clade Platanistoidea, having a well-diversified fossil record from the Late Oligocene to the Middle Miocene. Based on a partial skeleton collected from the Chilcatay Formation (Chilcatay Fm; southern coast of Peru), we report here a new squalodelphinid genus and species, Macrosqualodelphis ukupachai . A volcanic ash layer, sampled near the fossil, yielded the 40 Ar/ 39 Ar age of 18.78 ± 0.08 Ma (Burdigalian, Early Miocene). The phylogenetic analysis places Macrosqualodelphis as the earliest branching squalodelphinid. Combined with several cranial and dental features, the large body size (estimated body length of 3.5 m) of this odontocete suggests that it consumed larger prey than the other members of its family. Together with Huaridelphis raimondii and Notocetus vanbenedeni , both also found in the Chilcatay Fm, this new squalodelphinid further demonstrates the peculiar local diversity of the family along the southeastern Pacific coast, possibly related to their partition into different dietary niches. At a wider geographical scale, the morphological and ecological diversity of squalodelphinids confirms the major role played by platanistoids during the Early Miocene radiation of crown odontocetes.

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Boersma, Alexandra T., Matthew R. McCurry, and Nicholas D. Pyenson. "A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)." Royal Society Open Science 4, no. 5 (May 2017): 170022. http://dx.doi.org/10.1098/rsos.170022.

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Many odontocete groups have developed enlarged facial crests, although these crests differ in topography, composition and function. The most elaborate crests occur in the South Asian river dolphin ( Platanista gangetica ), in which they rise dorsally as delicate, pneumatized wings anterior of the facial bones. Their position wrapping around the melon suggests their involvement in sound propagation for echolocation. To better understand the origin of crests in this lineage, we examined facial crests among fossil and living Platanistoidea, including a new taxon, Dilophodelphis fordycei , nov. gen. and sp., described herein, from the Early Miocene Astoria Formation of Oregon, USA. We measured the physical extent and thickness of platanistoid crests, categorized their relative position and used computed tomography scans to examine their internal morphology and relative bone density. Integrating these traits in a phylogenetic context, we determined that the onset of crest elaboration or enlargement and the evolution of crest pneumatization among the platanistoids were separate events, with crest enlargement beginning in the Oligocene. However, we find no evidence for pneumatization until possibly the Early Miocene, although certainly by the Middle Miocene. Such an evolutionary context, including data from the fossil record, should inform modelling efforts that seek to understand the diversity of sound generation morphology in Odontoceti.

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Hulbert, Richard C., Richard M. Petkewich, Gale A. Bishop, David Bukry, and David P. Aleshire. "A new middle Eocene protocetid whale (Mammalia: Cetacea: Archaeoceti) and associated biota from Georgia." Journal of Paleontology 72, no. 5 (September 1998): 907–27. http://dx.doi.org/10.1017/s0022336000027232.

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A shallow-marine fossil biota was recovered from the Blue Bluff unit (formerly part of the McBean Formation) in the Upper Coastal Plain of eastern Georgia. Biochronologically significant mollusks (e.g., Turritella nasuta, Cubitostrea sellaeformis, Pteropsella lapidosa) and calcareous nannoplankton (e.g., Chiasmolithus solitus, Reticulofenestra umbilica, Cribocentrum reticulatum) indicate a latest Lutetian-earliest Bartonian age, or about 40 to 41 Ma. Georgiacetus vogtlensis new genus and species is described from a well-preserved, partial skeleton. Georgiacetus is the oldest known whale with a true pterygoid sinus fossa in its basicranium and a pelvis that did not articulate directly with the sacral vertebrae, two features whose acquisitions were important steps toward adaptation to a fully marine existence. The posterior four cheek teeth of G. vogtlensis form a series of carnassial-like shearing blades. These teeth also bear small, blunt accessory cusps, which are regarded as being homologous with the larger, sharper accessory cusps of basilosaurid cheek teeth.

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Tanaka, Yoshihiro, Hitoshi Furusawa, and Lawrence G. Barnes. "Fossil Herpetocetine Baleen Whales (Cetacea, Mysticeti, Cetotheriidae) from the Lower Pliocene Horokaoshirarika Formation at Numata, Hokkaido, Northern Japan." Paleontological Research 22, no. 4 (October 2018): 295–306. http://dx.doi.org/10.2517/2017pr025.

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Demere, Thomas A. "THE FOSSIL WHALE, BALAENOPTERA DAVIDSONII (COPE 1872), WITH A REVIEW OF OTHER NEOGENE SPECIES OF BALAENOPTERA (CETACEA: MYSTICETI)." Marine Mammal Science 2, no. 4 (October 1986): 277–98. http://dx.doi.org/10.1111/j.1748-7692.1986.tb00136.x.

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Pyenson, Nicholas D., and Simon N. Sponberg. "Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record." Journal of Mammalian Evolution 18, no. 4 (August 26, 2011): 269–88. http://dx.doi.org/10.1007/s10914-011-9170-1.

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Bisconti, Michelangelo, Dirk K. Munsterman, and Klaas Post. "A new balaenopterid whale from the late Miocene of the Southern North Sea Basin and the evolution of balaenopterid diversity (Cetacea, Mysticeti)." PeerJ 7 (May 17, 2019): e6915. http://dx.doi.org/10.7717/peerj.6915.

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Background Balaenopterid mysticetes represent the most successful family-rank group of this clade. Their evolutionary history is characterized by a rich fossil record but the origin of the living genera is still largely not understood. Recent discoveries in the southern border of the North Sea revealed a number of well preserved fossil balaenopterid whales that may help resolving this problem. In particular, skull NMR 14035 shares morphological characters with the living humpback whale, Megaptera novaeangliae and, for this reason, its characteristics are investigated here. Methods The comparative anatomical analysis of the new specimen formed the basis of a new phylogenetic analysis of the Mysticeti based on a matrix including 350 morphological character states scored for 82 Operational Taxonomic Units. The stratigraphic age of the specimen was determined based on the analysis of the dinocyst assemblage recovered in the associated sediment. We assessed clade diversity in Balaenopteridae by counting the numbers of clades in given time intervals and then plotted the results. Results Nehalaennia devossi n. gen. et sp. is described for the first time from the late Tortonian (8.7–8.1 Ma) of the Westerschelde (The Netherlands). This new taxon belongs to Balaenopteridae and shows a surprisingly high number of advanced characters in the skull morphology. Nehalaennia devossi is compared to a large sample of balaenopterid mysticetes and a phylogenetic analysis placed it as the sister group of a clade including the genus Archaebalaenoptera. The inclusion of this fossil allowed to propose a phylogenetic hypothesis for Balaenopteridae in which (1) Eschrichtiidae (gray whales) represents a family of its own, (2) Balaenopteridae + Eschrichtiidae form a monophyletic group (superfamily Balaenopteroidea), (3) Cetotheriidae is the sister group of Balaenopteroidea, (4) living Balaenoptera species form a monophyletic group and (5) living M. novaeangliae is the sister group of Balaenoptera. Our work reveals a complex phylogenetic history of Balaenopteridae and N. devossi informs us about the early morphological transformations in this family. Over time, this family experienced a number of diversity pulses suggesting that true evolutionary radiations had taken place. The paleoecological drivers of these pulses are then investigated.

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Collareta, Alberto, Olivier Lambert, Christian de Muizon, Mario Urbina, and Giovanni Bianucci. "<i>Koristocetus pescei</i> gen. et sp. nov., a diminutive sperm whale (Cetacea: Odontoceti: Kogiidae) from the late Miocene of Peru." Fossil Record 20, no. 2 (December 7, 2017): 259–78. http://dx.doi.org/10.5194/fr-20-259-2017.

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Abstract. Among odontocetes, members of the family Kogiidae (pygmy and dwarf sperm whales) are known as small-sized and in many respects enigmatic relatives of the great sperm whale Physeter macrocephalus. Most of the still scanty fossil record of Kogiidae is represented by isolated skulls and ear bones from Neogene deposits of the Northern Hemisphere, with the significant exception of Scaphokogia, a highly autapomorphic genus from late Miocene deposits of the Pisco Formation exposed along the southern coast of Peru. Here we report on a new fossil kogiid from Aguada de Lomas, a site where the late Miocene beds of the Pisco Formation are exposed. This specimen consists of an almost complete cranium representing a new taxon of Kogiidae: Koristocetus pescei gen. et sp. nov. Koristocetus mainly differs from extant Kogia spp. by displaying a larger temporal fossa and well-individualized dental alveoli on the upper jaws. Coupled with a relatively elongated rostrum, these characters suggest that Koristocetus retained some degree of raptorial feeding abilities, contrasting with the strong suction feeding specialization seen in Recent kogiids. Our phylogenetic analysis recognizes Koristocetus as the earliest branching member of the subfamily Kogiinae. Interestingly, Koristocetus shared the southern coast of present-day Peru with members of the genus Scaphokogia, whose unique convex rostrum and unusual neurocranial morphology seemingly indicate a peculiar foraging specialization that has still to be understood. In conclusion, Koristocetus evokes a long history of high diversity, morphological disparity, and sympatric habits in fossil kogiids, thus suggesting that our comprehension of the evolutionary history of pygmy and dwarf sperm whales is still far from being exhaustive.

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Geisler, Jonathan H., and Zhexi Luo. "The petrosal and inner ear of Herpetocetus sp. (Mammalia: Cetacea) and their implications for the phylogeny and hearing of archaic mysticetes." Journal of Paleontology 70, no. 6 (November 1996): 1045–66. http://dx.doi.org/10.1017/s0022336000038749.

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This paper describes the petrosal (periotic) and the inner ear of Herpetocetus sp., an archaic mysticete whale (Mysticeti, Mammalia) from the Yorktown Formation (Pliocene) of North Carolina, USA. Parsimony analysis of 28 petrosal characters of Herpetocetus sp. and 11 other cetacean taxa supports the monophyly of mysticetes and the division of odontocetes and mysticetes. The in-group taxa of this analysis are: Herpetocetus, Parietobalaena, Pelocetus, Balaenidae, Eschrichtius, and Balaenopteridae. Odontocetes and the archaeocete Zygorhiza were used as successive outgroups to root phylogenetic trees and to establish character polarities. Among the modern mysticetes, the Balaenopteridae (rorquals) and the Eschrichtiidae (gray whales) are more closely related to each other than either is to the Balaenidae (bowhead and right whales). Several Miocene “cetotheriid” mysticetes and balaenids share some resemblance in the petrosal, suggesting their affinities. Quantitative information of the inner ear of Herpetocetus sp. was obtained by serial sectioning and computer graphic reconstruction. Herpetocetus sp. is much less developed than odontocetes in the cochlear structures that are crucial for high frequency hearing. Some cochlear structures in this fossil mysticete resemble more closely the non-echolocating modern mysticetes than early fossil toothed whales, indicating a possible specialization in low frequency hearing. This suggests that the archaic mysticetes of the Miocene and Pliocene did not have high frequency hearing necessary for echolocation. Herpetocetus sp. is similar to modern mysticetes but different from odontocetes in the spherical shape of the vestibule.

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BISCONTI, MICHELANGELO. "Comparative osteology and phylogenetic relationships ofMiocaperea pulchra, the first fossil pygmy right whale genus and species (Cetacea, Mysticeti, Neobalaenidae)." Zoological Journal of the Linnean Society 166, no. 4 (November 26, 2012): 876–911. http://dx.doi.org/10.1111/j.1096-3642.2012.00862.x.

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de Buffrénil, Vivian, and Olivier Lambert. "Histology and growth pattern of the pachy-osteosclerotic premaxillae of the fossil beaked whale Aporotus recurvirostris (Mammalia, Cetacea, Odontoceti)." Geobios 44, no. 1 (January 2011): 45–56. http://dx.doi.org/10.1016/j.geobios.2010.09.001.

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McGowen, Michael R., Georgia Tsagkogeorga, Sandra Álvarez-Carretero, Mario dos Reis, Monika Struebig, Robert Deaville, Paul D. Jepson, et al. "Phylogenomic Resolution of the Cetacean Tree of Life Using Target Sequence Capture." Systematic Biology 69, no. 3 (October 21, 2019): 479–501. http://dx.doi.org/10.1093/sysbio/syz068.

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Abstract The evolution of cetaceans, from their early transition to an aquatic lifestyle to their subsequent diversification, has been the subject of numerous studies. However, although the higher-level relationships among cetacean families have been largely settled, several aspects of the systematics within these groups remain unresolved. Problematic clades include the oceanic dolphins (37 spp.), which have experienced a recent rapid radiation, and the beaked whales (22 spp.), which have not been investigated in detail using nuclear loci. The combined application of high-throughput sequencing with techniques that target specific genomic sequences provide a powerful means of rapidly generating large volumes of orthologous sequence data for use in phylogenomic studies. To elucidate the phylogenetic relationships within the Cetacea, we combined sequence capture with Illumina sequencing to generate data for $\sim $3200 protein-coding genes for 68 cetacean species and their close relatives including the pygmy hippopotamus. By combining data from $>$38,000 exons with existing sequences from 11 cetaceans and seven outgroup taxa, we produced the first comprehensive comparative genomic data set for cetaceans, spanning 6,527,596 aligned base pairs (bp) and 89 taxa. Phylogenetic trees reconstructed with maximum likelihood and Bayesian inference of concatenated loci, as well as with coalescence analyses of individual gene trees, produced mostly concordant and well-supported trees. Our results completely resolve the relationships among beaked whales as well as the contentious relationships among oceanic dolphins, especially the problematic subfamily Delphinidae. We carried out Bayesian estimation of species divergence times using MCMCTree and compared our complete data set to a subset of clocklike genes. Analyses using the complete data set consistently showed less variance in divergence times than the reduced data set. In addition, integration of new fossils (e.g., Mystacodon selenensis) indicates that the diversification of Crown Cetacea began before the Late Eocene and the divergence of Crown Delphinidae as early as the Middle Miocene. [Cetaceans; phylogenomics; Delphinidae; Ziphiidae; dolphins; whales.]

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Aguirre Fernández, Gabriel, Lawrence G. Barnes, Francisco J. Aranda Manteca, and Jorge R. Fernández Rivera. "Protoglobicephala mexicana, a new genus and species of Pliocene fossil dolphin (Cetacea; Odontoceti; Delphinidae) from the Gulf of California, Mexico." Boletín de la Sociedad Geológica Mexicana 61, no. 2 (2009): 245–65. http://dx.doi.org/10.18268/bsgm2009v61n2a13.

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Pyenson, Nicholas D., Jeremy A. Goldbogen, and Robert E. Shadwick. "Mandible allometry in extant and fossil Balaenopteridae (Cetacea: Mammalia): the largest vertebrate skeletal element and its role in rorqual lunge feeding." Biological Journal of the Linnean Society 108, no. 3 (December 17, 2012): 586–99. http://dx.doi.org/10.1111/j.1095-8312.2012.02032.x.

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Dumont, Maïtena, Vivian de Buffrénil, Ismael Miján, and Olivier Lambert. "Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whaleGlobicetus hiberus(Mammalia, Cetacea, Ziphiidae)." Journal of Morphology 277, no. 10 (July 15, 2016): 1292–308. http://dx.doi.org/10.1002/jmor.20575.

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Gearty, William, Craig R. McClain, and Jonathan L. Payne. "Energetic tradeoffs control the size distribution of aquatic mammals." Proceedings of the National Academy of Sciences 115, no. 16 (March 26, 2018): 4194–99. http://dx.doi.org/10.1073/pnas.1712629115.

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Four extant lineages of mammals have invaded and diversified in the water: Sirenia, Cetacea, Pinnipedia, and Lutrinae. Most of these aquatic clades are larger bodied, on average, than their closest land-dwelling relatives, but the extent to which potential ecological, biomechanical, and physiological controls contributed to this pattern remains untested quantitatively. Here, we use previously published data on the body masses of 3,859 living and 2,999 fossil mammal species to examine the evolutionary trajectories of body size in aquatic mammals through both comparative phylogenetic analysis and examination of the fossil record. Both methods indicate that the evolution of an aquatic lifestyle is driving three of the four extant aquatic mammal clades toward a size attractor at ∼500 kg. The existence of this body size attractor and the relatively rapid selection toward, and limited deviation from, this attractor rule out most hypothesized drivers of size increase. These three independent body size increases and a shared aquatic optimum size are consistent with control by differences in the scaling of energetic intake and cost functions with body size between the terrestrial and aquatic realms. Under this energetic model, thermoregulatory costs constrain minimum size, whereas limitations on feeding efficiency constrain maximum size. The optimum size occurs at an intermediate value where thermoregulatory costs are low but feeding efficiency remains high. Rather than being released from size pressures, water-dwelling mammals are driven and confined to larger body sizes by the strict energetic demands of the aquatic medium.

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Mourlam, Mickaël J., and Maeva J. Orliac. "Early evolution of the ossicular chain in Cetacea: into the middle ear gears of a semi-aquatic protocetid whale." Proceedings of the Royal Society B: Biological Sciences 286, no. 1912 (October 2, 2019): 20191417. http://dx.doi.org/10.1098/rspb.2019.1417.

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Modifications of the morphology and acoustic properties of the ossicular chain are among the major changes that accompanied the adaptation of Cetacea to the aquatic environment. Thus, data on the middle ear ossicles of early whales are crucial clues to understand the first steps of the emblematic terrestrial/aquatic transition that occurred in that group. Yet, the delicate nature and very small size of these bones make their preservation in the fossil record extremely rare. Due to the scarcity of available data, major questions remain concerning the sound transmission pathways in early non-fully aquatic whales. Virtual reconstruction of a partially complete ossicular chain of an Eocene protocetid whale documents for the first time the three ossicles of a semi-aquatic archaeocete. Contrary to previous hypotheses, these ossicles present different evolutionary patterns, showing that the ossicular chain does not act as a single morphological module. Functional analyses of the different middle ear units highlight a mosaic pattern of terrestrial and aquatic signatures. This integrative anatomical and functional study brings strong evidence that protocetids were adapted to their dual acoustic environment with efficient hearing in both air and water.

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Groves, Sabrina L., Carlos Mauricio Peredo, and Nicholas D. Pyenson. "What are the limits on whale ear bone size? Non-isometric scaling of the cetacean bulla." PeerJ 9 (February 5, 2021): e10882. http://dx.doi.org/10.7717/peerj.10882.

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The history of cetaceans demonstrates dramatic macroevolutionary changes that have aided their transformation from terrestrial to obligate aquatic mammals. Their fossil record shows extensive anatomical modifications that facilitate life in a marine environment. To better understand the constraints on this transition, we examined the physical dimensions of the bony auditory complex, in relation to body size, for both living and extinct cetaceans. We compared the dimensions of the tympanic bulla, a conch-shaped ear bone unique to cetaceans, with bizygomatic width—a proxy for cetacean body size. Our results demonstrate that cetacean ears scale non-isometrically with body size, with about 70% of variation explained by increases in bizygomatic width. Our results, which encompass the breadth of the whale fossil record, size diversity, and taxonomic distribution, suggest that functional auditory capacity is constrained by congruent factors related to cranial morphology, as opposed to allometrically scaling with body size.

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Lambert, Olivier, Christian de Muizon, Guy Duhamel, and Johannes Van Der Plicht. "Neogene and Quaternary fossil remains of beaked whales (Cetacea, Odontoceti, Ziphiidae) from deep-sea deposits off Crozet and Kerguelen islands, Southern Ocean." Geodiversitas 40, no. 2 (March 29, 2018): 135. http://dx.doi.org/10.5252/geodiversitas2018v40a6.

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Shipps, B. K., Carlos Mauricio Peredo, and Nicholas D. Pyenson. "Borealodon osedax , a new stem mysticete (Mammalia, Cetacea) from the Oligocene of Washington State and its implications for fossil whale-fall communities." Royal Society Open Science 6, no. 7 (July 2019): 182168. http://dx.doi.org/10.1098/rsos.182168.

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Baleen whales (mysticetes) lack teeth as adults and instead filter feed using keratinous baleen plates. They do not echolocate with ultrasonic frequencies like toothed whales but are instead known for infrasonic acoustics. Both baleen and infrasonic hearing are separately considered key innovations linked to their gigantism, evolutionary success and ecological diversity. The earliest mysticetes had teeth, and the phylogenetic position of many so-called toothed mysticetes remains debated, including those belonging to the nominal taxonomic groups Llanocetidae, Mammalodontidae and Aetiocetidae. Here, we report a new stem mysticete, Borealodon osedax gen. et sp. nov., from the Oligocene of Washington State, USA. Borealodon preserves multi-cusped teeth with apical wear; microCT scans of the inner ear indicate that the minimum frequency hearing limit of Borealodon was similar to mammalodontids. Borealodon is not recovered within a monophyletic Mammalodontidae nor a monophyletic Aetiocetidae; instead, it represents an unnamed lineage of stem Mysticeti, adding to the diversity of stem mysticetes, especially across the Rupelian–Chattian boundary. Furthermore, the presence of a putative chemosynthetic bivalve along with Osedax , a bone-boring annelid, found in association with the type specimen of Borealodon , offer more insights into the evolution of deep-sea whale-fall communities.

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Ramassamy, Benjamin, and Henrik Lauridsen. "A new specimen of Ziphiidae (Cetacea, Odontoceti) from the late Miocene of Denmark with morphological evidence for suction feeding behaviour." Royal Society Open Science 6, no. 10 (October 2019): 191347. http://dx.doi.org/10.1098/rsos.191347.

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A new fossil of Ziphiidae from the upper Miocene Gram Formation ( ca 9.9–7.2 Ma) is described herein. Computed tomographic scanning of the specimen was performed to visualize the mandibles and to obtain a three-dimensional digital reconstruction. It possesses several characters of the derived ziphiids, such as the dorsoventral thickening of the anterior process of the periotic, the dorsoventral compression of the pars cochlearis and the short unfused symphysis. The specimen cannot be identified beyond the family level, because of the unusual nature of the preserved parts consisting of the mandibles, earbones and postcranial remains. It differs from other ziphiid species from the Gram Formation, Dagonodum mojnum , in its larger size and the more derived morphology of its mandibles and earbones. Its long and thickened stylohyal, combined with its reduced teeth, suggests that this new specimen relied primarily on suction feeding. By contrast, the other ziphiid species from the Gram Formation, D. mojnum , shows adaptations for a more raptorial feeding strategy. Assuming the two species were coeval, their co-occurrence at the same locality with two different feeding strategies, may represent a case of niche separation. They may have hunted different types of prey, thus avoiding direct competition for the same food resource.

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Pyenson, Nicholas D., Jorge Vélez-Juarbe, Carolina S. Gutstein, Holly Little, Dioselina Vigil, and Aaron O’Dea. "Isthminia panamensis, a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of ‘river dolphins’ in the Americas." PeerJ 3 (September 1, 2015): e1227. http://dx.doi.org/10.7717/peerj.1227.

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ORLIAC, M. J., and S. DUCROCQ. "Eocene raoellids (Mammalia, Cetartiodactyla) outside the Indian Subcontinent: palaeogeographical implications." Geological Magazine 149, no. 1 (July 28, 2011): 80–92. http://dx.doi.org/10.1017/s0016756811000586.

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AbstractRaoellidae are small fossil cetartiodactyls closely related to the Cetacea. Until now undisputable raoellid remains were reported only from the early Middle Eocene of the Indian Subcontinent, although this Indo-Pakistani endemism has been challenged by several recent works describing potential raoellids from Mongolia, Myanmar and China. In this contribution we address the question of raoellid taxonomic content and definition, through a revision of the dental features of the family. This work, which includes a revision of the putative raoellid material from outside Indo-Pakistan, is primarily based on a re-examination of ‘suoid’ specimens from Shanghuang (Middle Eocene, coastal China). Our results indicate that the Shanghuang material both substantiates the youngest and easternmost occurrence of Raoellidae and represents the only unquestionable record of raoellids outside the Indian Subcontinent at present. This significantly extends the geographical and chronological range of the family. The occurrence of a raoellid species in the Middle Eocene of coastal China implies that raoellids dispersed from the Indian Subcontinent to eastern Asia during Early or Middle Eocene time. This tempers classical hypotheses of Middle Eocene Indian endemism and eastern Asian provincialism.

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Zheng, Jialu, Jianhua Wang, Zhen Gong, and Guan-Zhu Han. "Molecular fossils illuminate the evolution of retroviruses following a macroevolutionary transition from land to water." PLOS Pathogens 17, no. 7 (July 12, 2021): e1009730. http://dx.doi.org/10.1371/journal.ppat.1009730.

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The ancestor of cetaceans underwent a macroevolutionary transition from land to water early in the Eocene Period >50 million years ago. However, little is known about how diverse retroviruses evolved during this shift from terrestrial to aquatic environments. Did retroviruses transition into water accompanying their hosts? Did retroviruses infect cetaceans through cross-species transmission after cetaceans invaded the aquatic environments? Endogenous retroviruses (ERVs) provide important molecular fossils for tracing the evolution of retroviruses during this macroevolutionary transition. Here, we use a phylogenomic approach to study the origin and evolution of ERVs in cetaceans. We identify a total of 8,724 ERVs within the genomes of 25 cetaceans, and phylogenetic analyses suggest these ERVs cluster into 315 independent lineages, each of which represents one or more independent endogenization events. We find that cetacean ERVs originated through two possible routes. 298 ERV lineages may derive from retrovirus endogenization that occurred before or during the transition from land to water of cetaceans, and most of these cetacean ERVs were reaching evolutionary dead-ends. 17 ERV lineages are likely to arise from independent retrovirus endogenization events that occurred after the split of mysticetes and odontocetes, indicating that diverse retroviruses infected cetaceans through cross-species transmission from non-cetacean mammals after the transition to aquatic life of cetaceans. Both integration time and synteny analyses support the recent or ongoing activity of multiple retroviral lineages in cetaceans, some of which proliferated into hundreds of copies within the host genomes. Although ERVs only recorded a proportion of past retroviral infections, our findings illuminate the complex evolution of retroviruses during one of the most marked macroevolutionary transitions in vertebrate history.

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Bianucci, Giovanni, Claudio Di Celma, Mario Urbina, and Olivier Lambert. "New beaked whales from the late Miocene of Peru and evidence for convergent evolution in stem and crown Ziphiidae (Cetacea, Odontoceti)." PeerJ 4 (September 20, 2016): e2479. http://dx.doi.org/10.7717/peerj.2479.

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The Ziphiidae (beaked whales) represent a large group of open-ocean odontocetes (toothed cetaceans), whose elusive and deep diving behavior prevents direct observation in their natural habitat. Despite their generally large body size, broad geographical distribution, and high species number, ziphiids thus remain poorly known. Furthermore, the evolutionary processes that have led to their extreme adaptations and impressive extant diversity are still poorly understood. Here we report new fossil beaked whales from the late Miocene of the Pisco Formation (southern Peru). The best preserved remains here described are referred to two new genera and species, the MessinianChavinziphius maxillocristatusand the TortonianChimuziphius coloradensis, based on skull remains from two marine vertebrate-rich localities: Cerro Los Quesos and Cerro Colorado, respectively.C. maxillocristatusis medium sized retains a complete set of functional lower teeth, and bears robust rostral maxillary crests similar to those of the extantBerardius. By contrast,C. coloradensisis small and characterized by large triangular nasals and moderately thickened premaxillae that dorsally close the mesorostral groove. Both species confirm the high past diversity of Ziphiidae, the richest cetacean family in terms of the number of genera and species. Our new phylogenetic and biogeographical analyses depart markedly from earlier studies in dividing beaked whales into two major clades: theMessapicetusclade, which, along with other stem ziphiids, once dominated the southeastern Pacific and North Atlantic; and crown Ziphiidae, the majority of which are found in deep-water regions of the Southern Ocean, with possible subsequent dispersal both globally (MesoplodonandZiphius) and to the cooler waters of the northern oceans (BerardiusandHyperoodon). Despite this relatively clear separation, both lineages seem to follow similar evolutionary trends, including (1) a progressive reduction of dentition; (2) an increase in the compactness and thickness of the rostral bones; (3) similar changes in facial morphology (e.g., elevation of the vertex); and (4) an increase of body size. We suggest that these trends may be linked to a convergent ecological shift to deep diving and suction feeding.

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Bisconti, Michelangelo, Dirk K. Munsterman, René H. B. Fraaije, Mark E. J. Bosselaers, and Klaas Post. "A new species of rorqual whale (Cetacea, Mysticeti, Balaenopteridae) from the Late Miocene of the Southern North Sea Basin and the role of the North Atlantic in the paleobiogeography of Archaebalaenoptera." PeerJ 8 (January 13, 2020): e8315. http://dx.doi.org/10.7717/peerj.8315.

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Background The rich fossil record of rorqual and humpback whales (Cetacea, Mysticeti, Balaenopteridae) is mainly characterized by monotypic genera since genera including more than one species are extremely rare. The discovery of new species belonging to known genera would be of great importance in order to better understand ancestor-descendant relationships and paleobiogeographic patterns in this diverse group. Recent discoveries in the southern North Sea Basin yielded a number of reasonably well preserved fossil balaenopterids from the Late Miocene; this sample includes a balaenopterid skull from Liessel, The Netherlands, which shares key characters with Archaebalaenoptera castriarquati from the Pliocene of Mediterranean. This skull is permanently held by Oertijdmuseum, Boxtel, The Netherlands, with the number MAB002286 and is investigated here. Methods A detailed comparative anatomical analysis of the skull MAB002286 is performed in order to understand its relationships. The age of the skull is determined by dinocyst analysis of the associated sediment. A paleobiogeographic analysis is performed to understand paleobiogeographic patterns within the balaenopterid clade the new skull belongs to. Results Our work resulted in the description of Archaebalaenoptera liesselensis new species. The geological age of the holotype skull is between 8.1 and 7.5 Ma. The phylogenetic relationships of this species reveals that it is monophyletic with Archaebalaenoptera castriarquati from the Italian Pliocene. Moreover, in combination with a more basal species of Archaebalaenoptera from the late Miocene of Peru, our paleobiogeographic analysis suggests that the North Atlantic ocean played a major role as a center of origin of a number of balaenopterid clades including Protororqualus, Archaebalaenoptera and more advanced balaenopterid taxa. From a North Atlantic center of origin, two dispersal events are inferred that led to the origins of Archaebalaenoptera species in the South Pacific and Mediterranean. The distribution of Archaebalaenoptera was antitropical in the late Miocene. The role played by the Mediterranean salinity crisis is also investigated and discussed.

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Journal articles on the topic 'Cetacea, Fossil'

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