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Journal articles on the topic 'Fossil Xenarthra'

Author: Grafiati
Published: 4 June 2021
Last updated: 5 March 2023

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1

Gaudin, Timothy J., and William D. Turnbull. "The stapedial morphology of the Xenarthra and its implications for higher-level mammalian relationships." Paleontological Society Special Publications 6 (1992): 107. http://dx.doi.org/10.1017/s2475262200006675.

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The mammalian order Xenarthra (including the living Neotropical armadillos, anteaters, and tree sloths) has figured importantly in recent hypotheses of interordinal relationships among eutherian mammals. It has been suggested that the group shares a common ancestry both with the extant Old World order Pholidota (i.e. the pangolins or scaly-anteaters) and the extinct North American group Palaeanodonta. Furthermore, these three groups have been linked together into a monophyletic Cohort Edentata, which has been hypothesized to represent the sister-group to all other eutherians. This placement of edentates relative to the remainder of Eutheria has been supported in part by a purported difference in the morphology of the stapes in the two groups- edentates possessing a primitive, imperforate/columelliform morphology, other placentals a derived, perforate/stirrup-shaped morphology.A recent study of stapedial morphology among mammals by Novacek and Wyss (1986) suggests that within the Xenarthra itself a perforate stapes is found among armadillos, but that the pilosa in particular (the clade including anteaters and sloths) and the order as a whole are characterized primitively by an imperforate stapes. Our studies of the xenarthran ear region (Patterson et al., in press) have uncovered new ontogenetic and paleontological evidence which contradict the findings of Novacek and Wyss. Among adults of the two extant tree sloth genera, the stapes lacks a stapedial foramen. However, in both genera, this adult imperforate morphology is derived from a perforated juvenile stapes. Novacek and Wyss ignored fossil species in their consideration of the xenarthran stapes. It has long been known that extinct ground sloths of the family Mylodontidae possessed a large stapedial foramen. Unfortunately, until now no stapes were known from the remaining ground sloth families, the Megatheriidae and the Megalonychidae. We have uncovered a complete left stapes of an early Miocene megatheriid ground sloth Eucholoeops ingens. This stapes possesses a well-developed stapedial foramen. We believe that this new paleontological evidence, combined with our information on the ontogeny of the stapes in the living genera, clearly indicates that a perforate stapes is primitive for sloths. Moreover, when we plot distributions of stapedial morphologies of both living and fossil edentates onto a phylogeny of the Edentata, we can demonstrate that the a large stapedial foramen is primitive for the Xenarthra as a whole, and probably for the entire Cohort Edentata. Such a distribution makes it unlikely that stapedial morphology can be used to separate edentates from other eutherian mammals.
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2

Saarinen, Juha, and Aleksis Karme. "Tooth wear and diets of extant and fossil xenarthrans (Mammalia, Xenarthra) – Applying a new mesowear approach." Palaeogeography, Palaeoclimatology, Palaeoecology 476 (June 2017): 42–54. http://dx.doi.org/10.1016/j.palaeo.2017.03.027.

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3

Vizcaíno, Sergio F., and Gerardo De Iuliis. "Evidence for advanced carnivory in fossil armadillos (Mammalia: Xenarthra: Dasypodidae)." Paleobiology 29, no. 1 (2003): 123–38. http://dx.doi.org/10.1666/0094-8373(2003)029<0123:efacif>2.0.co;2.

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The euphractine Macroeuphractus outesi, from the late Pliocene Chapadmalalan SALMA of Buenos Aires Province, Argentina, is one of the largest dasypodids known. Its skull preserves features remarkable for an armadillo. Its complete dental arcade and large caniniform teeth have received attention in the literature as indicative of scavenging behavior. This report considers the degree of carnivory within the context of the generally omnivorous feeding behavior of euphractine armadillos through morphological and biomechanical analyses. Morphological analyses reveal that the main differences between M. outesi and other euphractines are the enlargement of the cranium, particularly of the temporal fossa; more prominent muscular scars for origin of the temporalis muscle; a more expanded rostrum, particularly in dorsoventral height; a more powerful anterior dentition, especially in the great enlargement and caniniform modification of M2; and a deeper and more robust zygomatic arch. Biomechanical analyses indicate that the moment arm of the temporalis musculature is greater than that recorded for other armadillos. These analyses indicate that the temporalis was probably larger and played a more important role in Macroeuphractus than in other euphractines, a pattern that is more usual for carnivorous mammals. Combined with the second upper molariform, which is caniniform, the features suggest that Macroeuphractus occupied an extreme position in the carnivorous-omnivorous feeding behavior of euphractines. Its large size indicates that it could have easily preyed on hare-sized vertebrates.
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Davis, Sarah N., Christopher R. Torres, Grace M. Musser, James V. Proffitt, Nicholas M. A. Crouch, Ernest L. Lundelius, Matthew C. Lamanna, and Julia A. Clarke. "New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica." PeerJ 8 (January 9, 2020): e8268. http://dx.doi.org/10.7717/peerj.8268.

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The middle–late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.
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Pujos, François, and Rodolfo Salas. "A systematic reassessment and paleogeographic review of fossil Xenarthra from Peru." Bulletin de l’Institut français d’études andines, no. 33 (2) (August 1, 2004): 331–77. http://dx.doi.org/10.4000/bifea.5746.

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6

Vizcaíno, Sergio F. "The teeth of the “toothless”: novelties and key innovations in the evolution of xenarthrans (Mammalia, Xenarthra)." Paleobiology 35, no. 3 (2009): 343–66. http://dx.doi.org/10.1666/0094-8373-35.3.343.

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A combination of historical, functional, and biomechanical constraints has shaped the masticatory apparatus of fossil and extant xenarthrans. Among the more notable features are the teeth: hypselodont; commonly reduced in size, complexity, and number; separated by short diastema; and composed of osteodentine. Enamel is absent, as are the cuspal patterns of other mammals. A comprehensive revision of teeth and other features of the masticatory apparatus of xenarthrans reveals that previous generalizations underestimate the morphological diversity and adaptive possibilities developed within the clade. The great diversity of forms suggests several such possibilities ranging from specialized myrmecophagous species to carrion feeders or predators among animalivores; selective browsers to bulk grazers among herbivores; and omnivores. In some cases xenarthrans represent less extreme versions of patterns developed in other major clades of mammals (marsupials, afrotheres, euarchontoglires, and laurasiatheres) clearly predetermined by a tribosphenic dental morphology, whereas in others they represent unique novelties indicative of particular biological roles. The combination of tooth features that characterize xenarthrans might be seen as the key innovation for the ecologic diversity developed at least since the Oligocene, breaking the mold of the tribosphenic condition that constrained the evolution of the other major clades of mammals.
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7

Billet, Guillaume, Lionel Hautier, and Renaud Lebrun. "Morphological diversity of the bony labyrinth (inner ear) in extant Xenarthrans and its relation to phylogeny." Journal of Mammalogy 96, no. 4 (May 26, 2015): 658–72. http://dx.doi.org/10.1093/jmammal/gyv074.

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Abstract We present a survey of the morphological diversity of the bony labyrinth of the inner ear in Xenarthra, including the fossil ground sloth Megatherium. Using a combination of traditional and geometric morphometrics, correlation analyses, and qualitative observations, we attempt to extract independent and informative phylogenetic characters of the bony labyrinth for the superorder. Geometric morphometric analyses demonstrate a strong imprint of phylogenetic history on the shape of the bony labyrinth of xenarthrans and a weak influence of allometry. Discrete characters mapped on a consensus cladogram for xenarthrans show support for many traditional nodes within the superorder and may also provide critical information for problematic nodes within Cingulata. A relatively large lateral semicircular canal may, for instance, represent a synapomorphy for the molecular clade allying fairy armadillos (Chlamyphorinae) to the Tolypeutinae. Striking convergences were detected when comparing Megatherium, the giant ground sloth, with extant armadillos and Chlamyphorus, the pink fairy armadillo, with the extant three- and two-toed sloths. These findings have the potential to help understand the phylogenetic relationships of fossil xenarthrans. Presentamos un estudio de la diversidad morfológica del laberinto óseo del oído interno de los xenartros, incluyendo el perezoso fósil Megatherium. Utilizamos una combinación de morfométrica tradicional y geométrica, análisis de correlación y observaciones cuantitativas para intentar extraer caracteres filogenéticos independientes e informativos del laberinto óseo para el superorden. Los análisis geométricos morfométricos muestran una fuerte impronta de la historia filogenética de la forma del laberinto óseo de los xenartros y una baja influencia de la alometría. Los caracteres discretos mapeados en un cladograma de consenso para xenartros apoyan varios nodos tradicionales dentro del superorden y podrían también brindar información importante para los nodos problemáticos dentro de los Cingulata. Un canal semicircular lateral relativamente largo podría, por ejemplo, representar una sinapomorfía que apoye el clado molecular que une a los pichiciegos con los Tolypeutinae. Se hallaron notables convergencias al comparar Megatherium con los armadillos actuales, y Chlamyphorus con los perezosos actuales. Estos hallazgos tienen el potencial para ayudar a entender las relaciones filogenéticas de los xenartros fósiles.
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8

Quiñones, Sofía I., Ángel R. Miño-Boilini, Alfredo E. Zurita, Silvina A. Contreras, Carlos A. Luna, Adriana M. Candela, María Camacho, Marcos D. Ercoli, Natalia Solís, and Diego Brandoni. "New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology." Journal of Paleontology 93, no. 06 (September 16, 2019): 1258–75. http://dx.doi.org/10.1017/jpa.2019.64.

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AbstractXenarthra is an endemic South American lineage of mammals, probably the sister clade of the other placental mammals. The oldest records of Xenarthra are from the latest Paleocene, although its current diversity is much lower than that recorded in some intervals of the Cenozoic Era. A new Neogene Xenarthra (Pilosa and Cingulata) assemblage from two localities of the Argentine Eastern Puna (Calahoyo and Casira) is described. The newly recorded taxa—Cingulata, Dasypodidae, Eutatini: Stenotatus sp. indet. and Eutatini indet., Euphractini: Macrochorobates scalabrinii (Moreno and Mercerat, 1891), and Tardigrada, Mylodontinae: cf. Simomylodon sp. indet. and Simomylodon cf. S. uccasamamensis Saint-André et al., 2010—and those already published from Calahoyo—Cingulata: Macrochorobates chapadmalensis (Ameghino, 1908), Eosclerocalyptus sp. indet., and Tardigrada, Megatheriidae: Pyramiodontherium bergi (Moreno and Mercerat, 1891)—suggest a middle–late Miocene age for the fossil-bearing levels. In Calahoyo, the presence of Stenotatus sp. indet., in addition to some rodents currently under study in the lower levels, suggest a closer similarity with the palaeofauna of Cerdas (southern Bolivia), probably involving the last part of the Miocene Climatic Optimum. The Xenarthra recorded in the middle and upper levels of Calahoyo and Casira suggest a late Miocene–Pliocene age. A comparative analysis between Calahoyo and Casira highlights the absence of Cingulata in the latter and a high diversity in the former. This situation probably indicates different paleoenvironmental conditions. Finally, we present the first certain record of the genus Simomylodon Saint-André et al., 2010 in Argentina, which includes the oldest record of dermal ossicles for sloths in South America.
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9

Toledo, N., M. S. Bargo, S. F. Vizcaíno, G. De Iuliis, and F. Pujos. "Evolution of body size in anteaters and sloths (Xenarthra, Pilosa): phylogeny, metabolism, diet and substrate preferences." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 106, no. 4 (December 2015): 289–301. http://dx.doi.org/10.1017/s1755691016000177.

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ABSTRACTPilosa include anteaters (Vermilingua) and sloths (Folivora). Modern tree sloths are represented by two genera, Bradypus and Choloepus (both around 4–6 kg), whereas the fossil record is very diverse, with approximately 90 genera ranging in age from the Oligocene to the early Holocene. Fossil sloths include four main clades, Megalonychidae, Megatheriidae, Nothrotheriidae, and Mylodontidae, ranging in size from tens of kilograms to several tons. Modern Vermilingua are represented by three genera, Cyclopes, Tamandua and Myrmecophaga, with a size range from 0.25 kg to about 30 kg, and their fossil record is scarce and fragmentary. The dependence of the body size on phylogenetic pattern of Pilosa is analysed here, according to current cladistic hypotheses. Orthonormal decomposition analysis and Abouheif C-mean were performed. Statistics were significantly different from the null-hypothesis, supporting the hypothesis that body size variation correlates with the phylogenetic pattern. Most of the correlation is concentrated within Vermilingua, and less within Mylodontidae, Megatheriidae, Nothrotheriidae and Megalonychidae. Influence of basal metabolic rate (BMR), dietary habits and substrate preference is discussed. In anteaters, specialised insectivory is proposed as the primary constraint on body size evolution. In the case of sloths, mylodontids, megatheriids and nothrotheriids show increasing body size through time; whereas megalonychids retain a wider diversity of sizes. Interplay between BMR and dietary habits appears to be the main factor in shaping evolution of sloth body size.
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10

Springer, Mark S., Robert W. Meredith, Jan E. Janecka, and William J. Murphy. "The historical biogeography of Mammalia." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1577 (September 12, 2011): 2478–502. http://dx.doi.org/10.1098/rstb.2011.0023.

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Palaeobiogeographic reconstructions are underpinned by phylogenies, divergence times and ancestral area reconstructions, which together yield ancestral area chronograms that provide a basis for proposing and testing hypotheses of dispersal and vicariance. Methods for area coding include multi-state coding with a single character, binary coding with multiple characters and string coding. Ancestral reconstruction methods are divided into parsimony versus Bayesian/likelihood approaches. We compared nine methods for reconstructing ancestral areas for placental mammals. Ambiguous reconstructions were a problem for all methods. Important differences resulted from coding areas based on the geographical ranges of extant species versus the geographical provenance of the oldest fossil for each lineage. Africa and South America were reconstructed as the ancestral areas for Afrotheria and Xenarthra, respectively. Most methods reconstructed Eurasia as the ancestral area for Boreoeutheria, Euarchontoglires and Laurasiatheria. The coincidence of molecular dates for the separation of Afrotheria and Xenarthra at approximately 100 Ma with the plate tectonic sundering of Africa and South America hints at the importance of vicariance in the early history of Placentalia. Dispersal has also been important including the origins of Madagascar's endemic mammal fauna. Further studies will benefit from increased taxon sampling and the application of new ancestral area reconstruction methods.
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dos Reis, Mario, Jun Inoue, Masami Hasegawa, Robert J. Asher, Philip C. J. Donoghue, and Ziheng Yang. "Phylogenomic datasets provide both precision and accuracy in estimating the timescale of placental mammal phylogeny." Proceedings of the Royal Society B: Biological Sciences 279, no. 1742 (May 23, 2012): 3491–500. http://dx.doi.org/10.1098/rspb.2012.0683.

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The fossil record suggests a rapid radiation of placental mammals following the Cretaceous–Paleogene (K–Pg) mass extinction 65 million years ago (Ma); nevertheless, molecular time estimates, while highly variable, are generally much older. Early molecular studies suffer from inadequate dating methods, reliance on the molecular clock, and simplistic and over-confident interpretations of the fossil record. More recent studies have used Bayesian dating methods that circumvent those issues, but the use of limited data has led to large estimation uncertainties, precluding a decisive conclusion on the timing of mammalian diversifications. Here we use a powerful Bayesian method to analyse 36 nuclear genomes and 274 mitochondrial genomes (20.6 million base pairs), combined with robust but flexible fossil calibrations. Our posterior time estimates suggest that marsupials diverged from eutherians 168–178 Ma, and crown Marsupialia diverged 64–84 Ma. Placentalia diverged 88–90 Ma, and present-day placental orders (except Primates and Xenarthra) originated in a ∼20 Myr window (45–65 Ma) after the K–Pg extinction. Therefore we reject a pre K–Pg model of placental ordinal diversification. We suggest other infamous instances of mismatch between molecular and palaeontological divergence time estimates will be resolved with this same approach.
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De Iuliis, Gerardo, Cástor Cartelle, and François Pujos. "New Pleistocene remains of megalonychid ground sloths (Xenarthra: Pilosa) from the intertropical Brazilian region." Journal of Paleontology 90, no. 3 (May 2016): 578–87. http://dx.doi.org/10.1017/jpa.2016.52.

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AbstractThe Pleistocene fossil slothAustralonyx aquaeDe Iuliis, Cartelle, and Pujos, 2009 (Mammalia, Xenarthra, Megalonychidae) was described from the intertropical region of Brazil. However, its mandible was not known and only cursory descriptions of the ear ossicles were included. The mandible was subsequently recognized among the remains originally collected from the type locality, and belongs to the holotype individual. As a particularly important skeletal element for specific recognition, it requires description to complement our understanding of this species. The ossicles, usually poorly represented in the fossil record, require further description to allow differentiation from those of other sloths. Comparisons of the mandible and ossicles are conducted with homologous elements of the contemporaneous and sympatricAhytherium aureumCartelle, De Iuliis, and Pujos, 2008, the only other megalonychid sloth known from intertropical Brazil, and reinforce the distinction between these two species detailed in their initial descriptions. Comparisons with other sloths (e.g.,Acratocnus,Megalonyx,Neocnus) also reveal differences withAu.aquaein such features as form and size of the caniniform tooth, angular process, and mandibular condyle. Differences among the malleus and incus ofAu.aquaeand several species of other sloth clades reveal clade level distinctions among Megatheriidae, Nothrotheriidae, and Megalonychidae. A well-preserved skull from the Brazilian state of Rondônia is noted as probably belonging toAu.aquae. This skull cannot be assigned formally to this species because it is not deposited in a recognized institution, but it does extend considerably the known range of the species.
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Billet, Guillaume, Lionel Hautier, Christian de Muizon, and Xavier Valentin. "Oldest cingulate skulls provide congruence between morphological and molecular scenarios of armadillo evolution." Proceedings of the Royal Society B: Biological Sciences 278, no. 1719 (February 2, 2011): 2791–97. http://dx.doi.org/10.1098/rspb.2010.2443.

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The cingulates of the mammalian order Xenarthra present a typical case of disagreement between molecular and morphological phylogenetic studies. We report here the discovery of two new skulls from the Late Oligocene Salla Beds of Bolivia (approx. 26 Ma), which are the oldest known well-preserved cranial remains of the group. A new taxon is described: Kuntinaru boliviensis gen. et sp. nov. A phylogenetic analysis clusters K. boliviensis together with the armadillo subfamily Tolypeutinae. These skulls document an early spotty occurrence for the Tolypeutinae at 26 Ma, in agreement with the temporal predictions of previous molecular studies. The fossil record of tolypeutines is now characterized by a unique occurrence in the Late Oligocene, and a subsequent 12 Myr lack in the fossil record. It is noteworthy that the tolypeutines remain decidedly marginal in the Late Palaeogene and Early Neogene deposits, whereas other cingulate groups diversify. Also, the anatomical phylogenetic analysis herein, which includes K. boliviensis , is congruent with recent molecular phylogenetic analyses. Kuntinaru boliviensis is the oldest confident calibration point available for the whole Cingulata.
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McAfee, Robert K. "Feeding mechanics and dietary implications in the fossil sloth Neocnus (Mammalia: Xenarthra: Megalonychidae) from haiti." Journal of Morphology 272, no. 10 (June 2, 2011): 1204–16. http://dx.doi.org/10.1002/jmor.10976.

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Pérez, Leandro M., Néstor Toledo, Florencia Mari, Ignacio Echeverría, Eduardo P. Tonni, and Marcelo J. Toledo. "Radiocarbon dates of fossil record assigned to mylodontids (Xenarthra - Folivora) found in Cueva del Milodón, Chile." Quaternary Science Reviews 251 (January 2021): 106695. http://dx.doi.org/10.1016/j.quascirev.2020.106695.

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Soibelzon, Esteban. "Using Paleoclimate and the Fossil Record to Explain Past and Present Distributions of Armadillos (Xenarthra, Dasypodidae)." Journal of Mammalian Evolution 26, no. 1 (May 25, 2017): 61–70. http://dx.doi.org/10.1007/s10914-017-9395-8.

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Ferreira, José D., Martín Zamorano, and Ana Maria Ribeiro. "On the fossil Remains of Panochthus Burmeister, 1866 (Xenarthra, Cingulata, Glyptodontidae) from the Pleistocene of southern Brazil." Anais da Academia Brasileira de Ciências 87, no. 1 (March 2015): 15–27. http://dx.doi.org/10.1590/0001-3765201520140012.

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The genus Panochthus represents the last lineage of "Panochthini" recorded in the Pleistocene. This genus has a wide latitudinal distribution in South America, and in Brazil it occurs in the southern and northeastern regions. In this paper we describe new material (isolated osteoderms and caudal tube fragments) assigned to Panochthus from the state of Rio Grande do Sul (southern Brazil) and discuss some taxonomic issues related to Panochthus tuberculatus and Panochthus greslebini based on this material . The occurrence of P. greslebini is the first for outside the Brazilian Intertropical Region. In addition, we describe new diagnostic features to differentiate the osteoderms of P. greslebini and P. tuberculatus. Unfortunately, it was not possible to identify some osteoderms at the species level. Interestingly, they showed four distinct morphotypes characterized by their external morphology, and thus were attributed to Panochthus sp. Lastly, we conclude that in addition to P.tuberculatus registered to southern Brazil, there is another species of the genus, assignable to P. cf. P. greslebini. Our analysis reinforce the reliability of caudal tube characters for the classification of species of Panochthus.
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Soibelzon, E., L. S. Avilla, and M. Castro. "The cingulates (Mammalia: Xenarthra) from the late Quaternary of northern Brazil: Fossil records, paleoclimates and displacements in America." Quaternary International 377 (August 2015): 118–25. http://dx.doi.org/10.1016/j.quaint.2015.02.052.

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Blanco, R. Ernesto, and Andrés Rinderknecht. "Fossil evidence of frequency range of hearing independent of body size in South American Pleistocene ground sloths (Mammalia, Xenarthra)." Comptes Rendus Palevol 11, no. 8 (November 2012): 549–54. http://dx.doi.org/10.1016/j.crpv.2012.07.003.

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Mendes, Millena Silva, Tábata Zanesco, Luíza Bomfim Melki, Caio César Rangel, Bruno Martins Ferreira, Cláudia Valéira Lima, Marlon André Oliveira, and Carlos Roberto dos Anjos Candeiro. "Eremotherium (Xenarthra, Mammalia) materials from the collections of Laboratório de Paleontologia e Evolução and Laboratório de Geologia of Universidade Federal de Goiás." Research, Society and Development 9, no. 7 (May 14, 2020): e316973951. http://dx.doi.org/10.33448/rsd-v9i7.3951.

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This study presents the first survey of fossil mammal specimens housed at the collections of the Federal University of Goiás. Here, we describe a set of associated femur and vertebrae fragments, one fragment of tibia, and two left and right maxillary fragments, identified as Eremotherium. Despite its fragmentary condition, the size and morphological aspect of the materials show diagnostic characteristics that suggest their relationship with Eremotherium. These new specimens described here contribute to the paleontology of the Goiás State, which may provide future research investments in collections not yet known, which may increase the knowledge on Pleistocene mammals of Central Brazil.
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Barasoain, Daniel, Rodrigo L. Tomassini, Alfredo E. Zurita, Claudia I. Montalvo, and Mariella Superina. "A new fairy armadillo (Cingulata, Chlamyphorinae) from the upper Miocene of Argentina: first fossil record of the most enigmatic Xenarthra." Journal of Vertebrate Paleontology 39, no. 5 (September 3, 2019): e1716778. http://dx.doi.org/10.1080/02724634.2019.1716778.

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ZURITA, ALFREDO E., MATÍAS TAGLIORETTI, MARTÍN DE LOS REYES, FRANCISCO CUADRELLI, and DANIEL POIRE. "Regarding the real diversity of Glyptodontidae (Mammalia, Xenarthra) in the late Pliocene (Chapadmalalan Age/Stage) of Argentina." Anais da Academia Brasileira de Ciências 88, no. 2 (June 7, 2016): 809–27. http://dx.doi.org/10.1590/0001-3765201620150113.

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ABSTRACT A large diversity of Glyptodontidae has been proposed as characterizing the Chapadmalalan Age (Pliocene). Most of these taxa were recognized on the basis of partial dorsal carapaces and/or caudal tubes, whereas the main diagnostic characteristic is a particular morphology of the exposed surface of the osteoderms. From a biostratigraphic point of view some species are biostratigraphically important. The Upper Chapadmalalan is based on the Paraglyptodon chapadmalensis biozone. Both the re-evaluation of the type and referred materials and new significant findings from the Chapadmalal and El Polvorín Formations indicate that the diversity of Pliocene Glyptodontidae is more limited than previously supposed. The particular morphology of the exposed surface of the osteoderms that characterizes some of the species actually corresponds to a taphonomic alteration, which results in a non-real ornamentation pattern. Thus, the Glyptodontinae P. chapadmalensis must be replaced as a fossil guide because neither this species nor the species included in the genera Urotherium, Trachycalyptus and Lomaphorus are well characterized. Taking into account the diversity of Glyptodontidae for this lapse, the Glyptodontinae are very scarce (a situation that contrasts with its records in the Pleistocene), whereas Eosclerocalyptus, "Plohophorini" (Plohophorus) and Doedicurinae (cf. Eleutherocercus antiquus) are among the most recorded taxa.
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Hubbe, Alex, Diogo Melo, and Gabriel Marroig. "A case study of extant and extinct Xenarthra cranium covariance structure: implications and applications to paleontology." Paleobiology 42, no. 3 (May 13, 2016): 465–88. http://dx.doi.org/10.1017/pab.2015.49.

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AbstractMost of the mammalian diversity is known only from fossils, and only a few of these fossils are well preserved or abundant. This undersampling poses serious problems for understanding mammalian phenotypic evolution under a quantitative genetics framework, since this framework requires estimation of a group’s additive genetic variance–covariance matrix (G matrix), which is impossible, and estimating a phenotypic variance–covariance matrix (P matrix) requires larger sample sizes than what is often available for extinct species. One alternative is to use G or P matrices from extant taxa as surrogates for the extinct ones. Although there are reasons to believe this approach is usually safe, it has not been fully explored. By thoroughly determining the extant and some extinct Xenarthra (Mammalia) cranium P matrices, this study aims to explore the feasibility of using extant G or P matrices as surrogates for the extinct ones and to provide guidelines regarding the reliability of this strategy and the necessary sample sizes. Variance–covariance and correlation P matrices for 35 cranium traits from 16 xenarthran genera (12 extant and 4 extinct) were estimated and compared between genera. Results show xenarthran P-matrix structures are usually very similar if sample sizes are reasonable. This study and others developed with extant therian mammals suggest, in general, that using extant G or P matrices as an approximation to extinct ones is a valid approach. Nevertheless, the accuracy of this approach depends on sample size, selected traits, and the type of matrix being considered.
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De Iuliis, Gerardo, María S. Bargo, and Sergio F. Vizcaíno. "Variation in skull morphology and mastication in the fossil giant armadillosPampatheriumspp. and allied genera (Mammalia: Xenarthra: Pampatheriidae), with comments on their systematics and distribution." Journal of Vertebrate Paleontology 20, no. 4 (January 19, 2001): 743–54. http://dx.doi.org/10.1671/0272-4634(2000)020[0743:vismam]2.0.co;2.

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Pérez, Leandro M., Néstor Toledo, Florencia Mari, Ignacio Echeverría, Eduardo P. Tonni, and Marcelo J. Toledo. "Corrigendum to “Radiocarbon dates of fossil record assigned to mylodontids (Xenarthra-Folivora) found in Cueva del Milodón, Chile” [Quat. Sci. Rev. 251 (2020) 106695]." Quaternary Science Reviews 258 (April 2021): 106886. http://dx.doi.org/10.1016/j.quascirev.2021.106886.

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26

Carrillo-Briceño, Jorge Domingo, Eli Amson, Alfredo Zurita, and Marcelo Ricardo Sánchez-Villagra. "Hermann Karsten (1817–1908): a German naturalist in the Neotropics and the significance of his paleovertebrate collection." Fossil Record 20, no. 1 (December 12, 2016): 21–36. http://dx.doi.org/10.5194/fr-20-21-2016.

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Abstract. During the mid-19th century, the German naturalist Hermann Karsten conducted a 12-year exploration (1844–1856) in the territories of Ecuador, New Granada (now Colombia) and Venezuela, allowing him to produce important botanic, geographic and geologic descriptions with valuable information that permits us to refer to him as a pioneer in many of these topics. With his return to Europe, abundant geological, paleontological and living plant specimens were brought and housed in European museums and botanical gardens. The Karsten collection included an important invertebrate collection from the Cretaceous of the Andes of Colombia and Venezuela, which was studied and published by himself and the renowned German paleontologist Leopold von Buch, filling a large void in the knowledge about ancients faunas. H. Karsten's vertebrate collection was never illustrated or subjected to a detailed taxonomic study, being mentioned in scientific publications in a repetitive manner and with incorrect taxonomic and provenance information. More than 160 years after they were collected, we carried out a taxonomic revision of all H. Karsten's vertebrate specimens from Colombia and Venezuela, which are housed in the Museum of Natural History in Berlin. These specimens are represented by cranial and postcranial elements of megafauna, which include Megatheriidae, Mylodontidae and Glyptodontidae (Xenarthra), Toxodontidae (Notoungulata), Gomphotheriidae (Proboscidea), and many other indeterminate mammal remains. This revision is intended to clarify the taxonomy and provenance of the specimens, emphasizing the historical importance of this fossil collection and its significance for the paleontology of the region.
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Krmpotic, C. M., M. R. Ciancio, C. Barbeito, R. C. Mario, and A. A. Carlini. "Osteoderm morphology in recent and fossil euphractine xenarthrans." Acta Zoologica 90, no. 4 (October 2009): 339–51. http://dx.doi.org/10.1111/j.1463-6395.2008.00359.x.

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Pérez, Leandro M., Néstor Toledo, Gerardo De Iuliis, M. Susana Bargo, and Sergio F. Vizcaíno. "Morphology and function of the hyoid apparatus of fossil xenarthrans (mammalia)." Journal of Morphology 271, no. 9 (August 12, 2010): 1119–33. http://dx.doi.org/10.1002/jmor.10859.

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29

White, Jennifer. "Indicators of locomotor habits in xenarthrans: Evidence for locomotor heterogeneity among fossil sloths." Journal of Vertebrate Paleontology 13, no. 2 (June 8, 1993): 230–42. http://dx.doi.org/10.1080/02724634.1993.10011502.

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30

Houssaye, Alexandra. "Inferences on the lifestyle of fossil xenarthrans based on limb long bone inner structure." Peer Community in Paleontology, no. 1 (September 21, 2018): 100001. http://dx.doi.org/10.24072/pci.paleo.100001.

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Kalthoff, Daniela C. "Microstructure of dental hard tissues in fossil and recent xenarthrans (Mammalia: Folivora and Cingulata)." Journal of Morphology 272, no. 6 (March 31, 2011): 641–61. http://dx.doi.org/10.1002/jmor.10937.

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32

De Iuliis, Gerardo. "Recent Progress and Future Prospects in Fossil Xenarthran Studies, with Emphasis on Current Methodology in Sloth Taxonomy." Journal of Mammalian Evolution 25, no. 4 (August 12, 2017): 449–58. http://dx.doi.org/10.1007/s10914-017-9407-8.

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Lopes, Renato, and Jamil Pereira. "Fossils of Scelidotheriinae Ameghino, 1904 (Xenarthra, Pilosa) in the Pleistocene deposits of Rio Grande do Sul, Brazil." Gaea - Journal of Geosciences 6, no. 1 (September 1, 2010): 44–52. http://dx.doi.org/10.4013/gaea.2010.61.05.

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34

Varela, Luciano, P. Sebastián Tambusso, Santiago J. Patiño, Mariana Di Giacomo, and Richard A. Fariña. "Potential Distribution of Fossil Xenarthrans in South America during the Late Pleistocene: co-Occurrence and Provincialism." Journal of Mammalian Evolution 25, no. 4 (July 23, 2017): 539–50. http://dx.doi.org/10.1007/s10914-017-9406-9.

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35

Cuitiño, José I., Sergio F. Vizcaíno, M. Susana Bargo, and Inés Aramendía. "Sedimentology and fossil vertebrates of the Santa Cruz Formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina." Andean Geology 46, no. 2 (May 31, 2019): 383. http://dx.doi.org/10.5027/andgeov46n2-3128.

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Lago Posadas is located at the foot of the Southern Patagonian Andes, in southwestern Argentina, where the early Miocene Santa Cruz Formation (SCF) shows thick and laterally continuous exposures. This region has been scarcely explored for fossil vertebrates since the first efforts by J.B. Hatcher in 1898-99. In this contribution, we performed sedimentologic and paleontological studies in order to reconstruct depositional environments and the associated fossil vertebrate fauna. Sedimentologic data suggest that the sedimentary record begins with restricted marine-estuarine deposits grading upward to fluvial floodplains and fluvial channels. Extensive floodplains, occasionally interrupted by low-sinuosity, sand-dominated channels, show dominant reddish coloration, moderate to low paleosol development, abundant crevasse splay sandstones and lack of vegetal remains, suggesting deposition in a low gradient, oxygenated setting under elevated sedimentation rates. Vertical stratigraphic trends are subtle, suggesting little paleoenvironmental changes during deposition of the whole SCF in this region. Paleocurrent directions, sandstone composition and paleogeographic reconstructions all indicate that deposition of the SCF was strongly associated to the contemporaneous uplift of the Andes. Fossil vertebrates analyzed are the result of our collecting effort and revision of museum collections. The faunal assemblage includes 31 taxa: 28 mammals and three birds. Mammals belong to the main groups recorded in other areas of the SCF (metatherians, xenarthrans, notoungulates, litopterns, astrapotheres and rodents). The assemblage allows a Santacrucian Age sensu lato assignment for the fauna at Lago Posadas. Taxonomic revisions of several taxa are necessary to further adjust the biostratigraphic significance of this association. The combined record of arboreal, browser and frugivores, on one side, and grazer mammals and rheas, on the other, suggest the presence of both trees and open environments. Frugivores, among primary consumers, and the secondary consumers guild are under-represented due to sample and fossil remain size biases. The sedimentologic and paleontological record of the SCF in Lago Posadas suggests that the uplift of the Southern Patagonian Andes acted as a primary control on basin subsidence and sediment supply, providing a special signature for sub-andean localities. However, previously registered climatic changes are poorly recorded in this study.
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GENISE, JORGE F., and JUAN L. FARINA. "Ants and xenarthrans involved in a Quaternary food web from Argentina as reflected by their fossil nests and palaeocaves." Lethaia 45, no. 3 (January 17, 2012): 411–22. http://dx.doi.org/10.1111/j.1502-3931.2011.00301.x.

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37

Buckley, Michael. "Ancient collagen reveals evolutionary history of the endemic South American ‘ungulates’." Proceedings of the Royal Society B: Biological Sciences 282, no. 1806 (May 7, 2015): 20142671. http://dx.doi.org/10.1098/rspb.2014.2671.

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Since the late eighteenth century, fossils of bizarre extinct creatures have been described from the Americas, revealing a previously unimagined chapter in the history of mammals. The most bizarre of these are the ‘native’ South American ungulates thought to represent a group of mammals that evolved in relative isolation on South America, but with an uncertain affinity to any particular placental lineage. Many authors have considered them descended from Laurasian ‘condylarths’, which also includes the probable ancestors of perissodactyls and artiodactyls, whereas others have placed them either closer to the uniquely South American xenarthrans (anteaters, armadillos and sloths) or the basal afrotherians (e.g. elephants and hyraxes). These hypotheses have been debated owing to conflicting morphological characteristics and the hitherto inability to retrieve molecular information. Of the ‘native’ South American mammals, only the toxodonts and litopterns persisted until the Late Pleistocene–Early Holocene. Owing to known difficulties in retrieving ancient DNA (aDNA) from specimens from warm climates, this research presents a molecular phylogeny for both Macrauchenia patachonica (Litopterna) and Toxodon platensis (Notoungulata) recovered using proteomics-based (liquid chromatography–tandem mass spectrometry) sequencing analyses of bone collagen. The results place both taxa in a clade that is monophyletic with the perissodactyls, which today are represented by horses, rhinoceroses and tapirs.
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Cerdeño, E., M. Reguero, and B. Vera. "Deseadan Archaeohyracidae (Notoungulata) from Quebrada Fiera (Mendoza, Argentina) in the paleobiogeographic context of the South American late Oligocene." Journal of Paleontology 84, no. 6 (November 2010): 1177–87. http://dx.doi.org/10.1666/10-024.1.

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Recent field work at the Deseadan (late Oligocene) locality of Quebrada Fiera (Mendoza Province, Argentina) has provided new fossil remains that greatly increased the faunal assemblage of this site. A good number of specimens correspond to the Family Archaeohyracidae (Notoungulata) and are presented in this paper. Most of them are recognized as a unique taxon, corresponding to the genus Archaeohyrax, characterized by the presence of a strong, shallow, wide sulcus on the labial side of the talonid of m3. At specific level, it is identified with the species A. suniensis previously recognized at Salla (Bolivia). Specimens with different tooth wear degree show an intraspecific variation in occlusal morphology comparable to that observed among the Bolivian material. In addition to A. suniensis, an isolated p2 is tentatively related to Archaeotypotherium, due to their hypsodont but rooted condition and larger size. Two other isolated lower molars from this site had been previously related to this genus but they are comparable to the new specimens ascribed to Archaeohyrax. The identification of Archaeotypotherium is not well supported at present, but if later confirmed, it would increase the temporal distribution of the genus, so far recorded in Tinguirirican (early Oligocene) localities of Chile and Argentina. The recognition of A. suniensis in Quebrada Fiera establishes a greater affinity with the lower latitude Deseadan fauna of Salla than with that from Patagonia, where the genus is represented by A. patagonicus. Other faunal elements from Quebrada Fiera, however, do not support this affinity with Bolivia. Xenarthrans or some marsupials are equivalent to those from Patagonia, while other taxa such as the recently described notohippid or a rare, tiny metatheria are at present exclusive for Mendoza. The increasing knowledge of the Quebrada Fiera assemblage contributes to a better understanding of the paleogeographic scenario of Southern South America during late Oligocene.
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Varela, Luciano, H. Gregory McDonald, and Richard Fariña. "Sexual dimorphism in the fossil ground sloth Lestodon armatus (Xenarthra, Folivora)." Historical Biology, June 10, 2021, 1–13. http://dx.doi.org/10.1080/08912963.2021.1933470.

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40

Viñola-Lopez, Lazaro W., Elson E. Core Suárez, Jorge Vélez-Juarbe, Juan N. Almonte Milan, and Jonathan I. Bloch. "The oldest known record of a ground sloth (Mammalia, Xenarthra, Folivora) from Hispaniola: evolutionary and paleobiogeographical implications." Journal of Paleontology, December 21, 2021, 1–8. http://dx.doi.org/10.1017/jpa.2021.109.

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Abstract Sloths were among the most diverse groups of land vertebrates that inhabited the Greater Antilles until their extinction in the middle-late Holocene following the arrival of humans to the islands. Although the fossil record of the group is well known from Quaternary deposits in Cuba, Hispaniola, and Puerto Rico, remains from older units are scarce, limiting our understanding of their evolution and biogeographic history. Here we report the oldest known fossil ground sloth from Hispaniola, represented by an unassociated partial tibia and scapula that are recognized as a single taxon from the late Miocene-early Pliocene of the Dominican Republic. The combination of characters observed on the tibia suggests a close relationship with Megalocnus, otherwise only known from the Pleistocene–Holocene of Cuba. These fossils fill a temporal gap between those previously known from the early Miocene of Cuba and those from Pleistocene–Holocene deposits in the region and provide additional support for a continuous presence of the group in the Greater Antilles since the Oligocene.
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BRANDONI, Diego, Daniel BARASOAIN, and Laureano R. GONZÁLEZ RUIZ. "Late Miocene Dasypodidae Gray, 1821(Xenarthra, Cingulata) from the Toro Negro Formation (Central Andes, Argentina): diversity and chronological and biogeographical implications." Comptes Rendus Palevol, no. 1 (January 16, 2023). http://dx.doi.org/10.5852/cr-palevol2023v22a1.

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Fossil remains herein described are referred to different species of Dasypodidae Gray, 1821 (Mammalia, Xenarthra, Cingulata) and come from the upper levels of the lower member (Late Miocene-Early Pliocene) of the Toro Negro Formation at Quebrada de Las Torrecillas, La Rioja Province, Argentina, where previous vertebrate records only include those of Pyramiodontherium scillatoyanei De Iuliis, Ré & Vizcaíno, 2004 (Mammalia, Xenarthra) and Opisthodactylus cf. kirchneri Noriega, Jordan, Vezzosi & Areta, 2017 (Aves, Rheidae). The remains of Dasypodidae herein presented include Vetelia ghandii Esteban & Nasif, 1996, Chasicotatus peiranoi Esteban & Nasif, 1996, Macrochorobates scalabrinii (Moreno & Mercerat, 1891), Prozaedyus sp., and Paleuphractus argentinus (Moreno & Mercerat, 1891), and constitute the first records of these species for the Toro Negro Formation, increasing the mammal diversity for this unit. The association of dasypodids here described shows strong affinities with those described for Late Miocene localities of Northwestern Argentina. Under these evidences, the Dasypodidae here reported for Quebrada de Las Torrecillas site show a characteristic association of taxa from Northwestern Argentina, suggesting a Messinian age (Late Miocene) for the bearing levels of the Toro Negro Formation. In this way, these records support the accurate ages recently proposed for the lower Member of the Toro Negro Formation (i.e., Late Miocene-Early Pliocene).
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do Amaral, Roberta Veronese, João Alves de Oliveira, and Luciana Barbosa de Carvalho. "Comparative multivariate analysis of 3-D reconstructed encephalon in extant and fossil Folivora (Pilosa) and other representatives Xenarthra." Historical Biology, March 11, 2021, 1–9. http://dx.doi.org/10.1080/08912963.2021.1891418.

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43

Machado, Fabio A., Gabriel Marroig, and Alex Hubbe. "The pre-eminent role of directional selection in generating extreme morphological change in glyptodonts (Cingulata; Xenarthra)." Proceedings of the Royal Society B: Biological Sciences 289, no. 1967 (January 19, 2022). http://dx.doi.org/10.1098/rspb.2021.2521.

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The prevalence of stasis on macroevolution has been classically taken as evidence of the strong role of stabilizing selection in constraining morphological change. Rates of evolution calculated over longer timescales tend to fall below the expected under genetic drift, suggesting that directional selection signals are erased at longer timescales. Here, we investigated the rates of morphological evolution of the skull in a fossil lineage that underwent extreme morphological modification, the glyptodonts. Contrary to what was expected, we show here that directional selection was the primary process during the evolution of glyptodonts. Furthermore, the reconstruction of selection patterns shows that traits selected to generate a glyptodont morphology are markedly different from those operating on extant armadillos. Changes in both direction and magnitude of selection are probably tied to glyptodonts' invasion of a specialist-herbivore adaptive zone. These results suggest that directional selection might have played a more critical role in the evolution of extreme morphologies than previously imagined.
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Tauber, Adan Alejo, Federico Álvarez, Gastón Martínez, José Augusto Haro, Jerónimo Matías Krapovickas, and Gastón Leonardo Nieto. "Nuevos sitios fosilíferos y evolución paleoambiental del cenozoico tardío del suroeste de Córdoba, Argentina." Andean Geology 49, no. 1 (November 22, 2021). http://dx.doi.org/10.5027/andgeov49n1-3316.

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New fossil remains were found in Neogene and quaternary sedimentary sequences exposed in Alpa Corral and río San Bartolomé localities (Rio Cuarto Department, Córdoba, Argentina). They were assigned to Nopachtus cabrerai (Xenarthra, Cingulata, Glyptodontidae), Notiomastodon platensis (Proboscidea, Gomphotheriidae) and cf. Trigodon gaudryi (Notoungulata, Toxodontidae), and traces of the Scoyenia ichnofacies, as Taenidium barretti, were identified. Based on these findings, we conclude that: 1, the species Nopachtus cabrerai and cf. Trigodon gaudryi are registered for the first time in the Sierras Pampeanas region and support (along with the rest of the known taxa) a clear faunistic similarity to the Pampean region; 2, the beginning of the Neogene sedimentation in the Alpa Corral area (Las Barrancas river and San Bartolome river) would have started during the early Pliocene (Montehermosan Age); 3, the paleoenvironment would have been a fluvial system, with meandering canals interspersed with paleosols developed in floodplains with overflow deposits or abandoned meanders; 4, the paleontological and sedimentary record suggests a well-marked diachronism (from west-southwest to east-northeast) between the beginning of the Neogene sedimentation in the southern sector of San Alberto valley (late Miocene [Huayquerian Age]), the Alpa Corral region (early Pliocene [Monthermosan Age), and Río La Cruz valley (late Pliocene [Chapadmalalan Age]).
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45

Platt, BF. "The foraging pits of the nine-banded armadillo, Dasypus novemcinctus (Mammalia: Xenarthra: Dasypodidae), and implications for interpreting conical trace fossils." Palaeontologia Electronica, 2014. http://dx.doi.org/10.26879/496.

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46

Vizcaino, Sergio Fabián, M. Susana Bargo, M. Encarnación Pérez, Inés Aramendía, José Ignacio Cuitiño, Eduardo Sebastián Monsalvo, Evangelos Vlachos, Jorge Ignacio Noriega, and Richard Frederick Kay. "Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina." Andean Geology 49, no. 3 (June 7, 2022). http://dx.doi.org/10.5027/andgeov49n3-3425.

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The early–middle Miocene continental Cerro Boleadoras Formation (CBF) crops out in the area of Cerro Boleadoras and Cerro Plomo on the western slope of the Meseta del Lago Buenos Aires, northwestern Santa Cruz Province, Argentina. The lower levels of the CBF consist of laterally extensive medium to pebbly sandstone beds with trough cross-bedding, interpreted as fluvial channel deposits, interbedded with tabular fine-grained floodplain deposits. Recent fieldwork provided fossil vertebrates from these levels with an estimated age between ~16.5 Ma and 15.1 Ma (late Burdigalian-early Langhian). The studied section temporally overlaps with the middle or upper sections of the Santa Cruz Formation (SCF) in the Austral–Magallanes Basin of southern Patagonia, the Río Frias Formations in Chile, and the lower Collón-Curá Formation of northern Patagonia. We compile an integrated faunal list for this locality, including specimens from previous collections, and discuss its chronological and paleoenvironmental implications. The taxa list includes most of the groups recorded in the SCF: one anuran, three birds, and at least 33 mammals (metatherians, xenarthrans, litopterns, notoungulate typotheres and caviomorph rodents), indicating a Santacrucian age sensu lato. We also recorded a testudine, which constitutes the southernmost record of tortoises in South America and worldwide. Faunal differences between the vertebrate fossil content of the CBF and the mentioned sections of the Santa Cruz, Río Frías and Collón-Curá formations may reflect ecologic, climatic and geographic differences rather than temporal ones. The co-occurrence of arboreal or semiarboreal, browsing, frugivorous, and grazing mammals suggests the presence of both trees and open environments for the area occupied by the CBF rocks. However, it is not possible to discern whether these two environments coexisted or alternated, and whether one environment predominated over the other. Marker taxa, such as the chinchillid rodents Prolagostomus and Pliolagostomus, and the typothere Pachyrukhos indicate a trend to aridification during the Miocene in southern Patagonia, as previously reported for the upper part of the SCF along the Río Santa Cruz and south to the Río Coyle, along the Atlantic coast and the Río Gallegos.
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