Source for the above is Bargo et al. Blik paa Brasiliens Dyreverden for Sidste Jordomvaeltning. Fjerde Afhandling: Fortsaettelse af Pattedyrene. Palaeogeography, Palaeoclimatology, Palaeoecology , Barbosa, Fernando Henrique de Souza et al. In Press,
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Left hand of this species Quick Facts Common Name: Wandering giant ground sloth About two dozen skeletons of Eremotherium eomigrans were recovered from ancient lake sediments represented by the Haile 7C and 7G fossil sites.
The mounted skeleton on display at the Florida Museum of Natural History is a composite primarily consisting of bones from two similar-sized individuals.
Two very different size groups are represented by full grown adult individuals, presumably representing sexual dimorphism. In most mammals in which this is the case, the males are larger than the females, but in living tree sloths, females are slightly larger than males.
So it is therefore unclear which size group represents which sex in Eremotherium. The name refers to the likelihood that this species was the first of its genus and family to migrate to North America from South America. Map of Florida, with highlights indicating counties where fossils of the species have been found Alternate Scientific Names: none Overall Geographic Range This species is known mainly from Florida.
Fields et al. It is believed that xenarthrans branched off from the rest of placental mammals earlier than any other clade within Mammalia, and are thus a very old lineage. Major lineages within Xenarthra are also very ancient, such that the three families of ground sloths recognized in Florida—the Mylodontidae, the Megalonychidae, and Megatheriidae—had already diverged by the Paleogene Period Hulbert, As an old group, xenarthrans are fairly distinct anatomically and are characterized by a number of unique features including 1 an extra articulation on their lumbar and sometimes thoracic vertebrae called xenopophyses, 2 enamel-less, often fairly homogenous, ever-growing teeth, 3 a secondary spinous process on the scapula, and 4 an articular surface between the sacrum and one or more caudal vertebrae Hulbert, Xenarthrans originated in South America and were distributed almost exclusively to that continent for much of their history.
During the event known as the Great American Biotic Interchange GABI , several xenarthran taxa migrated to North America before and after the formation of the land bridge between the two continents at the Isthmus of Panama 3 million year ago.
The first record of xenarthrans in North America is from the late Miocene of Florida, about 9 million years ago, which preserve fossils of giant ground sloths of the families Megalonychidae and Mylodontidae. Eremotherium eomigrans is an extinct species of giant ground sloth that belongs to a third family, the Megatheriidae, that first migrated to North America in the late Pliocene or very early Pleistocene Hulbert, Eremotherium eomigrans is the first of its family to disperse to North America De Iuliis and Cartelle, Figure 2.
Skull of UF , Eremotherium eomigrans in A ventral, B dorsal, and C right lateral views, and the first right lower molariform tooth of the same specimen in D right lateral and E occlusal views. Figure 3. Hindlimb elements of Eremotherium eomigrans. A A left femur UF anterior view, with image flipped across a vertical axis; B a right tibia and fibula UF in anterior view; C a right third pedal digit UF in left lateral view; D a right calcaneum UF in dorsal view; and a right astragalus UF in E ventral and F dorsal views.
Abbreviations: a. Eremotherium eomigrans was one of the largest species of giant ground sloth known from North America along with its close relative, Eremotherium laurillardi. Large individuals of Eremotherium may have weighed as much as 3 tons Hulbert, Fossils of Eremotherium eomigrans are not found as widespread as the later-occuring Eremotherium laurillardi which is known from North, Central and South America in the late Pleistocene Cartelle and De Iuliis, This species was at first only known from Florida, but specimens from Dorchester County, South Carolina, have also been attributed to Eremotherium eomigrans based on the likely Blancan age of the locality in which they were found Fields et al.
So there is no evidence that the two species overlapped in time. Figure 4. The dorsal view of the left hand of UF , the holotype skeleton of Eremotherium eomigrans. Anatomically, Eremotherium eomigrans is very similar to Eremotherium laurillardi, and the former species may be ancestral to the latter. The cranium Figure 2 and dental anatomy of the two species is almost impossible to distinguish, and the general size and shape of many of the postcranial bones are similar between the two species and fall within the range of variation for each other De Iuliis and Cartelle, The teeth of Eremotherium are large, rectangular when viewed occlusally , and have a unique v-shaped valley in lateral view Fig.
Both species had 5 upper and 4 lower teeth in each side of the jaw, with upper and lower crowns interlocking along the V-shaped valleys into what was likely a shearing surface for processing leaves and small branches Hulbert, Eremotherium eomigrans in general had slightly more gracile postcranial bones Fig. The major diagnostic feature of Eremotherium eomigrans is its manus or hand; Fig. Eremotherlium laurillardi has only 3 digits they have lost digits 1 and 2 and another closely related megatheriid giant ground sloth, Megatherium americanum, has 4 digits with a loss of digit 1.
While Eremotherium eomigrans is similar to Megatherium americanum in size and in some anatomical features such as more slender metacarpals, the former species is characterized by a shallower maxilla with reduced hypsodonty of the upper teeth compared to the latter species. Eremotherium eomigrans and Eremotherium laurillardi are also probably more closely related to each other than either is to Megatherium based on their shared characteristics of a rugose ectotympanic bone on the skull and the contiguous nature of the articular facet for the atlas first cervical vertebra on the axis second cervical vertebra De Iuliis and Cartelle, Because many specimens of Eremotherium eomigrans have been found, there is some understanding of variation within the species.
Like Eremotherium laurillardi, it is thought that Eremotherium eomigrans exhibited a high degree of sexual dimorphism in body size. This is based on the size distribution of individuals, which seems to indicate that adult individuals of a larger size and of a smaller size existed within the same population De Iluiis and Cartelle, Furthermore, Eremotherium eomigrans varied in the morphology of their wrist carpal and hand bones such that two variant forms can be recognized.
These two forms are differentiated based on which bones are fused together in what is known as the metacarpal-carpal-complex MCC.
The MCC in one variation consists of a fusion of the metacarpal 1, trapezium, and the trapezoid bones Fig. The second variation has a MCC composed of just the fused metacarpal 1 and trapezium Fig. In these two variants, the shape of articulation surface of the second metacarpal with the MCC also differs based on the type of MCC the individual possessed.
However, Eremotherium laurillardi, which is thought to have evolved from Eremotherium eomigrans, had a MCC with a fused trapezoid, and lost two digits in its manus. The functional significance of these variants and the loss of fingers in later Eremotherium is unknown De Iluiis and Cartelle, Figure 5.
Hand and wrist bones of Eremotherium eomigrans. Articular surfaces on the MCC are labeled with the name of the bones with which they articulate. Abbreviations: m.
Die Stirnlinie verlief deutlich gerade und nicht so gewellt wie bei Megatherium. Der nach unten weisende Knochenfortsatz stand deutlich steiler als bei anderen Faultieren. Das Augenfenster war flach und klein und etwas tiefer gelegen als bei Megatherium oder bei den heutigen Faultieren. Bei Eremotherium war dadurch der Unterkiefer unterhalb der Symphyse 14,5 cm tief, unterhalb des zweiten Zahns 15 cm und unterhalb des vierten 12,5 cm. Der Kronenfortsatz stieg bis zu 27 cm auf, der Gelenkfortsatz war nur wenig niedriger.