As we’ve seen before
there are several horse-like taxa in the mammal family tree. Known for over 150 years and worldwide in dispersal, the chalicotheres (Figs. 1-3) had claw-like hooves on an otherwise horse-like body and skull.
Because several taxa
in the large reptile tree have horse-like traits, the ability to split and lump these taxa is being taxed. Moreover, the outgroup for the chalicotheres has shifted with the addition of more closely related taxa.
nests close to the base of the chalicotheres, close to tapirs and other extinct South American mammals.
(Fig. 2) is a basal chalicothere with round, hoof-like hooves. Basal taxa have four metacarpals. The fourth one is reduced on later taxa. What looks like a Pteranodon-like crest would have been layered with strong jaw muscles.
(Fig. 2) had a domed cranium, distinct from other chalicotheres.
(Fig. 2) had a short, primate-like face, distinct from other chalicotheres.
(Fig. 3) is another derived chalicothere with longer forelimbs, no tail and probably sat on its large buttocks while feeding.
as the study proceeds…
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