(Mammalia: Xenarthra) from the Late Miocene of Uruguay

Journal of Vertebrate Paleontology 23(4):981±983, December 2003 ᭧ 2003 by the Society of Vertebrate Paleontology

NOTE

AN ENIGMATIC CINGULATA (MAMMALIA: XENARTHRA) FROM THE LATE MIOCENE OF URUGUAY

SERGIO F. VIZCAIÂNO1, ANDREÂ S RINDERKNECHT 2, and ADA CZERWONOGORA3, 1Departamento CientõÂ®co PaleontologõÂa de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina (CONICET); 2Museo Nacional de Historia Natural de Montevideo, Casilla de correo 399, 11000, Montevideo, Uruguay; 3Departamento de PaleontologõÂa, Facultad de Ciencias, IguaÂ 4225, 11400 Montevideo, Uruguay

Cingulates, the armadillos (Dasypodidae), glyptodonts (Glyptodonti- absent along the posterior margin (Fig. 1). The peripheral ®gures are dae) and pampatheres (Pampatheriidae), are perhaps the most distinctive separated by radial sulci. As in N. originalis, foramina are located in xenarthrans, as their bony carapaces make them easily recognizable. the intersection of the principal and the radial sulci. They are interpreted Dasypodids are known from the late Paleocene to the Recent and glyp- as hair follicles as in living armadillos. The number of foramina cor- todonts and pampatheres from the late Eocene (following Kay et al., relates with the number of peripheral ®gures. The most conspicuous 1999) and Miocene (Carlini et al., 1989; Carlini and Scillato-YaneÂ, difference from N. originalis is that the foramina are more numerous 1993) to the Pleistocene±early Holocene of South America (Scillato- and smaller. YaneÂ, 1995). They were abundant, and in the Pliocene all three families dispersed into North America as part of the Great American Biotic DISCUSSION Interchange (Stehli and Webb, 1985). They are taxonomically diverse; systematically complex, and distinguished mainly on characters of or- In addition to Glyptatelus, Clypeotherium, and Neoglyptatelus, two namentation of the carapace and caudal tube. Herein we report the pres- other taxa have tentatively been included in the Glyptatelinae: the poor- ence of an enigmatic cingulate from the late Miocene of Uruguay (col- ly known Eocene Lomaphorelus depstus Ameghino by Mones (1986) lected in late 1988 by Luis R. Castiglioni) that we tentatively consider and the late Pliocene±early Pleistocene (Blancan and Irvingtonian as a glyptodont belonging to the genus Neoglyptatelus, of the poorly LMA) Pachyarmatherium leiseyi Downing and White by McKenna and known subfamily Glyptatelinae. Bell (1997). L. depstus is based on a very poorly preserved osteoderm Paula Couto (1979) recognized only four subfamilies within the without diagnostic features (Scillato-YaneÂ, 1977), so it is regarded here Glyptodontidae, Propalaeohoplophorinae, Hoplophorinae, Doedicurinae as a nomen dubium. and Glyptodontinae. However, a ®fth, the Glyptatelinae, which includes Webb et al. (1989:96) noted the presence of ``a new small glypto- the earliest and most primitive glyptodonts, is also generally recognized dont'' in the early Pleistocene of Florida. However, in the formal de- (Castellanos, 1932; Hoffstetter, 1958; Scillato-YaneÂ, 1977; Carlini et al., scription of Pachyarmatherium leiseyi, Downing and White (1995) pro- 1997; McKenna and Bell, 1997). Glyptatelines are known from a min- visionally regarded it as a dasypodoid with a combination of features imum of three genera, Glyptatelus (late Eocene to late Oligocene; Mus- associated with armadillos and glyptodonts. While the characters that tersan and Deseadan LMAs, following Kay et al., 1999), Clypeotherium would indicate dasypodoid rather than glyptodontoid af®nity were based (late Oligocene; Deseadan LMA), and Neoglyptatelus (middle to late primarily on features not related to the carapace, they noted that its Miocene; Laventan and Huayquerian LMAs). osteoderms resembled those of Glyptatelus. While there is much more Abbreviations LMA, Land Mammal Age; x, average; s, standard to be learned about this animal, especially its cranial features, it was deviation; n, sample size; OR, observed range; MNHN, Museo Na- tentatively listed by McKenna and Bell (1997) as a glyptateline glyp- cional de Historia Natural de Montevideo, Uruguay. todontid. Much of the evidence that P. leiseyi was a dasypodoid and not a glyptodont was based on a ``poorly restored and mounted specimen under less than ideal conditions'' (Downing and White, 1995:384) SYSTEMATIC PALEONTOLOGY that belonged in a private collection and was not ®gured in the paper. Superorder XENARTHRA Cope, 1889 Pachyarmatherium leiseyi has a glyptodont-like carapace, but it dif- Order CINGULATA Illiger, 1811 fers from those of classic glyptodonts in being divided into two parts Family GLYPTODONTIDAE Gray, 1869 with a movable ``hinge'' between them. However, the presence of mov- Subfamily GLYPTATELINAE Castellanos, 1932 able bands represents the primitive condition for glyptodonts, as they NEOGLYPTATELUS Carlini, VizcaõÂno, and Scillato-YaneÂ, 1997 are present in the early Miocene Propalaeohoplophorinae (Scott, 1903± NEOGLYPTATELUS sp. 1904). The osteoderms of Pachyarmatherium are very similar to those of Neoglyptatelus (SFV, pers. obs.), and the large foramina make them Referred Specimen MNHN 1483, 45 complete and 12 broken iso- more similar to N. originalis than those of MNHN 1483. Thus, Neo- lated osteoderms belonging to the same individual (Fig. 1). glyptatelus could be a junior synonym of Pachyarmatherium. Never- Locality and Horizon Uruguay, San JoseÂ Department, erosional theless, the available information on other parts of the skeleton is not surface of Puerto ArazatõÂ Beach, 3 to 4 km east of El Sauce Creek (Fig. de®nitive enough to demonstrate conclusively this synonymy. 2); greenish sandy basal mudstone of the upper Miocene Camacho For- The description of the postcrania of P. leiseyi by Downing and White mation (Ubilla et al., 1990; Perea et al., 1994, 1996). (1995) would indicate an armadillo-like form. Nevertheless, most of the Measurements (mm) Length: x ϭ 13.98, s ϭ 2.49, n ϭ 38, OR characters, such as the presence of claws instead of hooves and free ϭ 10.6±19.7. Width: x ϭ 12.76, s ϭ 1.71, n ϭ 37, OR ϭ 9.2±16.4. dorsal vertebrae, are primitive features of cingulates. Free dorsal ver- Thickness: x ϭ 6.81, s ϭ 0.84; n ϭ 39, OR ϭ 5.4±8.2. tebrae were also reported with material of Neoglyptatelus from Colom- Description Most of the osteoderms are pentagonal or hexagonal bia (Carlini et al., 1997). It is noteworthy that glyptatelines are one of in outline (Fig. 1). Their size is within the range of Neoglyptatelus the oldest groups recognized as glyptodonts and that their postcrania originalis, and much smaller (approximately one third to one half in are almost unknown. Therefore, they could have retained many ple- length) than the older glyptatelines, Glyptatelus and Clypeotherium. The siomorphic features. On the other hand, Carlini et al. (1997) tentatively surface is smooth as in Glyptatelus and N. originalis. They have a attributed a very glyptodont-like mandible with teeth to Neoglyptatelus, straight-sided principal ®gure that frequently reaches the posterior mar- as is that of Glyptatelus (Simpson, 1948). gin, as in N. originalis. The principal ®gure is separated from three to Several questions remain to be addressed. First, the similarity of os- six peripheral ®gures by the principal sulcus. The peripheral ®gures are teoderm morphology suggests that Neoglyptatelus and Pachyarmath- well developed on the anterior and lateral sides and less developed or erium are the same genus, and the latter should be the valid name. But

981 982 JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 23, NO. 4, 2003

FIGURE 1. Dorsal and lateral views of MNHN 1483, osteoderms of Neoglyptatelus sp. from Puerto ArazatõÂ Beach, 3 to 4 km east of El Sauce Creek, San JoseÂ Department, Uruguay (Fig. 2). FIGURE 2. Map of the region where Neoglyptatelus sp. was collected on the east margin of the La Plata River. The arrow indicates the precise geographic location where MNHN 1483 was found. the crania and postcrania of the type species of both genera, N. originalis and P. leiseyi, remain poorly known and a better understanding of the skeleton is necessary to make an informed taxonomic decision. Ad- ditionally, the great difference in geologic age and geographic distance ern expansion. Perhaps the smaller size and number of foramina (hair separating them makes it currently more acceptable to remain conser- follicles?) indicates warmer conditions at the Uruguay site than in La vative and keep them separated. Hence, we refrain from synonymizing Venta. The southern record of this tropical genus might correlate with them and refer the specimen from Uruguay to Neoglyptatelus. the contemporaneous southernmost range extension of the turtle Phry- Second, we believe that the thickness of the osteoderms and the lack nops geoffroanus (De la Fuente, 1992). Living representatives of Phry- of any movable bands of osteoderms such as those present on pam- nops inhabit freshwater lowlands in tropical to humid temperate cli- patheres and dasypodids is indicative that both Neoglyptatelus and mates. According to Perea et al. (1996), the record of P. geoffroanus Pachyarmatherium are glyptodontoids. Nevertheless, their phylogenetic in the Camacho Formation is in agreement with estuarine, ¯uvio-deltaic, position within the cingulates, in particular, and the glyptatelines, in or coastal environments. Acknowledgments We express our gratitude to several persons and general, remains uncertain. Third, if the phylogenetic hypothesis that P. Â leiseyi is a glyptateline glyptodontid (as suggested by McKenna and institutions. Richard A. FarinÄa, Alvaro Mones, Daniel Perea, Gustavo Bell, 1997) is followed, it would represent a signi®cant extension of the Scillato-YaneÂ, David Webb and Richard Hulbert reviewed earlier ver- geographic and chronologic distribution of the subfamily. Finally, if sions of the manuscript. Their comments and suggestions, although not either Pachyarmatherium or Neoglyptatelus were not glyptodontoids, completely followed by us, were insightful and helpful. John Flynn (Field Museum of Natural History, FMNH), Bruce MacFadden (Florida then they would represent a peculiar example of convergence within Â the cingulates. The thickening of the osteoderms observed in Pachyar- Museum of Natural History), Alvaro Mones (MNHN) and Richard Ted- matherium would have been derived separately from that of the glyp- ford (American Museum of Natural History, AMNH) facilitated access todontids, as originally proposed by Downing and White (1995). to collections of their institutions. Research trips by SFV to North The Uruguayan specimen of Neoglyptatelus was collected from the America museums were partially supported by a FMNH Visitor Schol- erosional surface of Puerto ArazatõÂ Beach on the east margin of the La arship grant and an AMNH Theodore Roosevelt grant, respectively. Plata River (Fig. 2). The sediments were originally described as the KiyuÂ Formation (Francis and Mones, 1965), but are now considered a LITERATURE CITED parallic facies of the Camacho Formation (da Silva, 1990). They have Bossi, J., and R. Navarro. 1991. GeologõÂa del Uruguay. Departamento also been included in the RaigoÂn Formation (Preciozzi et al., 1985; de publicaciones de la Universidad de la RepuÂblica 2:463±970. Bossi and Navarro, 1991). Castellanos, A. 1932. Nuevos geÂneros de glyptodontes en relacioÂn a su Previously, the Glyptatelinae were restricted to the late Eocene (Mus- ®logenia. Physis 11:92±100. tersan LMA) to late Oligocene (Deseadan LMA) of Argentina, late Ol- Carlini, A. A., and G. J. Scillato-YaneÂ. 1993. Origin and evolution of igocene (Deseadan LMA) of Bolivia, and middle Miocene (Laventan ``glyptodontoids.'' Journal of Vertebrate Paleontology 13(3 suppl.): LMA) of Colombia. Faunistic analyses by Perea et al. (1989, 1994, 28A. 1996) strongly suggest correlation between the sediments where the ÐÐÐ, S. F. VizcaõÂno, and G. J. Scillato-YaneÂ. 1989. Novedosos Cin- osteoderms were found and the ItuzaingoÂ Formation in Argentina. The gulata (Mammalia, Xenarthra) del Mioceno de Ecuador. 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