Digital Cranial Endocasts of the Extinct Sloth Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina: Description and Comparison with the Extant Sloths

Boscaini, Alberto; Iurino, Dawid A.; Sardella, Raffaele; Tirao, G.; Gaudin, Timothy J.; Pujos, François

doi:10.1007/s10914-018-9441-1

Cited by 23 publications

(49 citation statements)

References 52 publications

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“…More posteriorly, at the level of the squamosal, parietal, and occipital bones, pneumatization is less dense or missing ( Figure 5). This set of features is more similar to that of Choloepus (Boscaini et al, 2020) than that of other extinct giant sloths like Glossotherium robustum (Boscaini et al, 2020) and Paramylodon harlani (Stock, 1925), where the sinuses invade every bone all the way back to the occiput.…”

Section: Cranial Sinusesmentioning

confidence: 65%

“…The squamosal of MNHN-Bol V 13364 is partially pneumatized, with large sinuses in its anteriormost portion, invading the tip of the zygomatic process (Figures 5A-C). However, the posterior half of the squamosal is not pneumatized (Figures 5A-C), in contrast to Glossotherium, Choloepus and Bradypus (Boscaini et al, 2020). It should be noted that the squamosal pneumatization of the extant sloths is an epitympanic sinus continuous with the tympanic cavity ventrally, whereas that of Catonyx and Glossotherium is confined to the squamosal itself, as is typical for mylodontids (Gaudin, 1995).…”

Section: Cranial Sinusesmentioning

confidence: 88%

“…It should be noted that the squamosal pneumatization of the extant sloths is an epitympanic sinus continuous with the tympanic cavity ventrally, whereas that of Catonyx and Glossotherium is confined to the squamosal itself, as is typical for mylodontids (Gaudin, 1995). Parietal sinuses are observable in Catonyx, but only in proximity to the frontoparietal suture (Figures 5A-C), as in Choloepus (Boscaini et al, 2020). In comparison to the frontal sinuses, the parietal sinuses are smaller in size, allowing observation of the underlying brain cavity in dorsal and lateral views (Figures 5A-C).…”

Section: Cranial Sinusesmentioning

confidence: 91%

“…The comparative sample is largely based on the dataset assembled by Boscaini et al (2020), which includes the two extant sloth species Bradypus variegatus and Choloepus hoffmanni, and the extinct giant mylodontine Glossotherium robustum. For the purposes of comparison, other non-digital endocranial information was obtained from Gervais (1869) and Dechaseaux (1958Dechaseaux ( , 1962aDechaseaux ( ,b, 1971.…”

Section: Methodsmentioning

confidence: 99%

“…Frontal sinuses merge posteriorly with the orbitosphenoid and the alisphenoid sinuses. In fact, the latter bones are also largely pneumatized at the level of the common aperture for the optic foramen and sphenorbital fissure ( Figure 5C), a common feature in extant and extinct sloths (Boscaini et al, 2020).…”

Section: Cranial Sinusesmentioning

confidence: 99%

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Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia

Boscaini

Iurino

Quispe³

et al. 2020

Front. Ecol. Evol.

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Extinct scelidotheriine sloths are among the most peculiar fossil mammals from South America. In recent decades, the external cranial anatomy of Pleistocene scelidotheres such as Scelidotherium, Catonyx, and Valgipes has been the subject of numerous studies, but their endocranial anatomy remains almost completely unknown. Today, computed tomographic (CT) scanning methodologies permit the exploration of previously inaccessible anatomical areas through a completely non-destructive process. For this reason, we undertook an analysis of the external and internal cranial anatomy of Catonyx tarijensis from the late Pleistocene of the Department of Oruro, in southwestern Bolivia. One particularly well-preserved specimen allowed detailed observation of all the main cranial osteological features, including the ear region and an almost complete hyoid apparatus, previously unknown for this taxon. Moreover, CT-scanning and subsequent elaboration of digital models of this specimen allowed observation of the brain cavity and cranial sinuses, and reconstruction of the trajectory of the main cranial nerves for the first time in an extinct scelidotheriine sloth. Additionally, we recovered the first three-dimensional reconstructions of the nasal cavity and the turbinates of an extinct sloth. In contrast to the usual depiction, the combined information from the external and internal anatomy suggests reduced lingual protrusion in Catonyx tarijensis, or at least a consistently more limited protrusion of the tongue in comparison with other mylodontid sloths such as Glossotherium robustum. The new morphological information recovered from this extinct sloth is compared with the available information for both extant and extinct forms, providing insights in the paleobiology of the extinct species. The present study reveals the importance of applying these novel non-destructive techniques to elucidate the evolutionary history of sloths.

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Section: Cranial Sinusesmentioning

confidence: 65%

Section: Cranial Sinusesmentioning

confidence: 88%

Section: Cranial Sinusesmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Cranial Sinusesmentioning

confidence: 99%

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Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia

Boscaini

Iurino

Quispe³

et al. 2020

Front. Ecol. Evol.

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Cranial osteology of a juvenile specimen ofAcratocnus ye(Mammalia, Xenarthra, Folivora) and its ontogenetic and phylogenetic implications

Gaudin

Scaife

2022

The Anatomical Record

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The present study comprises a description of the skull and jaw anatomy of a juvenile specimen of the Antillean sloth Acratocnus ye, from the Holocene of Haiti. Detailed descriptions and illustrations are provided of the skull bones and their sutural connections, which normally fuse in adults. Descriptions are also provided for the mandible and ear ossicles, as well as endocranial surfaces and sinuses exposed by breaks. The anatomy of our juvenile A. ye is compared to that of adult A. ye to assess ontogenetic changes in the skull. Several of these ontogenetic features are significant new observations that impact the relationships within Xenarthra as a whole, or between Xenarthrans and other placental mammals, most notably, the presence of a separate mesethmoid element, the presence of alveoli for a lower deciduous canine and anterior incisor, and the presence of separate rostral and caudal entotympanic elements. A full list of such changes are provided. In addition, the specimen provides information on phylogenetically relevant characters, including features unique to the genus Acratocnus, and features of the clade Choloepodini, including Acratocnus, the smaller extinct Antillean sloth Neocnus, and the extant two-toed sloth Choloepus. Contrary to previous studies, Acratocnus shares as many features with Choloepus as it does with its fellow Antillean form Neocnus in the present study, which is consistent with current morphology-based phylogenetic hypotheses regarding the relationships within Choloepodini. The current study highlights the need for further anatomical and phylogenetic investigations of Antillean sloths (Megalocnidae/Megalonychidae), and juvenile sloths in general.

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Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America

Fontoura

Ferreira

Bubadué

et al. 2020

Journal of Morphology

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A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.

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Digital Cranial Endocasts of the Extinct Sloth Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina: Description and Comparison with the Extant Sloths

Cited by 23 publications

References 52 publications

Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia

Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia

Cranial osteology of a juvenile specimen ofAcratocnus ye(Mammalia, Xenarthra, Folivora) and its ontogenetic and phylogenetic implications

Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America

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