Pampahippus secundus: a new Toxodont Notoungulate From Eocene Paleogene Argentina

A new Eocene Toxodontia (Mammalia, Notoungulata) from northwestern Argentina

Authors:

Deraco et al

Abstract:

A new species of Toxodontia (Mammalia, Notoungulata), Pampahippus secundus sp. nov., is described based on remains recovered from outcrops of the Lumbrera Formation exposed in Salta Province, northwest Argentina. The material studied consists of mandibular, maxillary, and premaxillary fragments with complete and incomplete teeth representing at least three individuals. It differs from the type species P. arenalesi by its smaller size and the presence of several dental features: I2 smaller than the I1 and I3, paraconule absent on the P3, upper molars wider than long and subquadrangular, with a single crista projecting from the ectoloph, strong mesiolingual cingulum surrounding the protocone on the M1, conspicuous metacone fold on the ectoloph of M1 and M2, and absence of labial cingulids on lower molars. In order to determine the phylogenetic position of P. secundus as well as different Paleogene notoungulates of northwestern Argentina, we performed a cladistic analysis. This analysis supports the paraphyly of Notohippidae proposed by previous authors and validates the monophyly of the genus Pampahippus, which ranks as a relatively basal taxon within Toxodontia. This contribution illustrates the significant and yet poorly known diversity of Paleogene toxodontians from northwestern Argentina and the importance of their study in the reconstruction of the evolutionary history of Notoungulata.

More Evidence South American Notoungulates are Perissodactyls

Ancient collagen reveals evolutionary history of the endemic South American ‘ungulates’

Author:

Buckley

Abstract:

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.

This came out just a hair behind the other paper.   I wonder which one was submitted first?

An Impressive Hegetothere Notoungulate Assemblage from Oligocene Paleogene Argentina

The Hegetotheriidae (Mammalia, Notoungulata) assemblage from the late Oligocene of Mendoza, central-western Argentina

Authors:

Cerdeño et al

Abstract:

This study describes new remains of Hegetotheriidae (Notoungulata), including a new species, from the Deseadan (late Oligocene) of Quebrada Fiera, Mendoza Province, Argentina. The assemblage is composed of four hegetotheriines, Prohegetotherium cf. P. sculptum, Prohegetotherium sp., Prohegetotherium schiaffinoi, and Prohegetotherium malalhuense, sp. nov., and the pachyrukhine Propachyrucos cf. P. simpsoni. The presence of Prosotherium cannot be totally discounted because lower molariforms are rather similar between the two pachyrukhine genera. The new species Prohegetotherium malalhuense, sp. nov., differs from all previously described hegetotheriines by having a lingually projecting, sharp parastyle and marked parastyle groove on the ectoloph of M2–3; talonid of m1–2 posterolabially projected; talonid of m3 with marked posterolabial groove; and the smaller size. Its phylogenetic affinities are not well resolved. Prohegetotherium is paraphyletic, with P. sculptum sister taxon to the remaining hegetotheres, and the new taxon more closely related to Hegetotherium mirabile than to P. schiaffinoi. The recognition of P. schiaffinoi and Prohegetotherium cf. P. sculptum emphasizes that the fauna from Quebrada Fiera shares elements with roughly contemporaneous Deseadan faunas from northern and southern latitudes, but important faunal particularities distinguish the region as well. The record of pachyrukhines at Quebrada Fiera more closely resembles Deseadan faunas in Patagonia than temporally correlative faunas from Bolivia and Uruguay, and indicates the presence of suitable habitats in mid-latitudes of Argentina for this hypselodont clade. Faunal affinities together with particular taxa from Quebrada Fiera appear to support a significant faunal provinciality in South America during the late Oligocene.

Mystery Solved: South American Ungulates (NotoUngulates) are Crown Perissodactyls (Horse, Rhino Cousins)

Ancient proteins resolve the evolutionary history of Darwin’s South American ungulates

Authors:

Welker et al

Abstract:

No large group of recently extinct placental mammals remains as evolutionarily cryptic as the approximately 280 genera grouped as ‘South American native ungulates’. To Charles Darwin , who first collected their remains, they included perhaps the ‘strangest animal[s] ever discovered’. Today, much like 180 years ago, it is no clearer whether they had one origin or several, arose before or after the Cretaceous/Palaeogene transition 66.2 million years ago or are more likely to belong with the elephants and sirenians of superorder Afrotheria than with the euungulates (cattle, horses, and allies) of superorder Laurasiatheria . Morphology-based analyses have proved unconvincing because convergences are pervasive among unrelated ungulate-like placentals. Approaches using ancient DNA have also been unsuccessful, probably because of rapid DNA degradation in semitropical and temperate deposits. Here we apply proteomic analysis to screen bone samples of the Late Quaternary South American native ungulate taxa Toxodon (Notoungulata) and Macrauchenia (Litopterna) for phylogenetically informative protein sequences. For each ungulate, we obtain approximately 90% direct sequence coverage of type I collagen α1- and α2-chains, representing approximately 900 of 1,140 amino-acid residues for each subunit. A phylogeny is estimated from an alignment of these fossil sequences with collagen (I) gene transcripts from available mammalian genomes or mass spectrometrically derived sequence data obtained for this study. The resulting consensus tree agrees well with recent higher-level mammalian phylogenies. Toxodon and Macrauchenia form a monophyletic group whose sister taxon is not Afrotheria or any of its constituent clades as recently claimed , but instead crown Perissodactyla (horses, tapirs, and rhinoceroses). These results are consistent with the origin of at least some South American native ungulates from ‘condylarths’, a paraphyletic assembly of archaic placentals. With ongoing improvements in instrumentation and analytical procedures, proteomics may produce a revolution in systematics such as that achieved by genomics, but with the possibility of reaching much further back in time.

pop sci link.

Reconstruction of the dentition of Propyrotherium saxeum

Reconstruction of the dentition of Propyrotherium saxeum Ameghino, 1901 (Mammalia, Pyrotheria): taxonomic and phylogenetic implications

Authors:

Kramarz et al

Abstract:

Propyrotherium saxeum is one the least known members of Pyrotheria, an enigmatic group of extinct, giant, endemic South American ‘ungulates.’ The species was originally described based upon two isolated cheek teeth and two tusk fragments. Later authors assigned additional isolated teeth to this taxon, but the position within the tooth row of all these teeth remained uncertain, preventing an accurate dental characterization and taxonomic distinction from other related species. Here we reexamine the type specimens of P. saxeum and additional materials previously reported as belonging to this species, and analyze several lots of still undescribed specimens, in order to reconstruct the cheek tooth series. Based on comparisons with better known pyrotheres, we conclude that the most probable cheek teeth formula is P2–M3/p2–m3. The cheek teeth gradually increase in size from front to back, and the upper cheek teeth have a gradual increase in loph curvature, as in Pyrotherium. All cheek teeth are bilophodont, but in premolars the anterior loph/id is transversely shorter than the posterior. All have lingual/labial cingulum/id; P3–M3 are subquadratic and three-rooted; p4–m3 are longer than wide, two-rooted, and bear a variably developed vestige of cristid obliqua. Propyrotherium is distinguishable from Griphodon and Baguatherium, but the distinction between these latter two taxa is uncertain with the current evidence. A revised cladistic analysis confirms that Propyrotherium is one of the earliest diverging pyrotheriids, but the resolution of its relationship with Griphodon and Baguatherium requires further evidence.

Late Pleistocene Toxodont Fossil Found in North America (USA)

The First Occurrence of a Toxodont (Mammalia, Notoungulata) in the United States

Authors:

1. Ernest L Lundelius (a,*)
2. Vaugn M Bryant (b)
3. Rolfe Mandel (c)
4. Kenneth J Thies (d)
5. Alston Thomas (b)

Affiliations:

a. Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78712, U.S.A.

b. Department of Anthropology, Texas A&M University (TAMU 4352), College Station, Texas 77843-4352, U.S.A.

c. Kansas Geological Survey, University of Kansas, Lawrence, Kansas 66047, U.S.A.,

d. 410618 Lynbrook Dr., Houston, Texas 77042, U.S.A.

*. Corresponding Author: erniel@mail.utexas.edu

Abstract:

Toxodonts were a group of large-sized notoungulates of South American origin. They were diverse and widespread in South America in deposits ranging in age from late Oligocene to late Pleistocene. Sparse remains have been found from the Pleistocene of isolated regions of Central America. All of the Central American specimens have been referred to the genus Mixotoxodon (Van Frank, 1950). They were not previously known north of the southern Mexican states of Michoacan and Veracruz, except for an unconfirmed report of an occurrence in Tamaulipas (Arroyo-Cabrales et al., 2010). Here we report the occurrence of a single toxodont tooth, a left upper third molar, from late Pleistocene deposits in Harris County, Texas (30◦N). This is the first record of toxodonts, or any notoungulate, in the United States and extends the geographic range of this group
1600 km north of their previously known localities at Hihuitl ´ an, Michoacan (18◦52 30 N, 103◦24 14 W) and La Estribera, Veracruz (18◦07 01.27 N, 94◦53 15.59W) (Polaco et al., 2004) to latitude 30◦N.