Two antelopes enter the LRT together

Suggested by a reader (thank you!),
the dik-dik (Madoqua kirkii, Fig. 1) and the sable antelope (Hippotragus niger, Fig. 2) enter the large reptile tree (LRT, 2050+ taxa, Fig. 3) together as derived members of the Artiodactyla.

Figure 1. Skulls of the dik-dik (Madoqua) shown to scale on a 72 dpi monitor. Arrow points to alveolus for an abset canine. The lower view is shot from a different angle that shows more occiput. Even so the proportion of the orbit vs cranium is different in the two specimens. The upper specimen is younger. It has no horn cores. Note the light yellow tubes, otic (ear) canals and their ontogenetic changes.

Madoqua kirkii
(Günther 1880; 45cm tall) is the extant dik-dik, a small antelope from Africa. Note the lacrimal depression and an orbit longer than the cranium in the top (younger) specimen only. Here this tiny antelope nests with the larger sable antelope, derived from cattle + giraffes and small fanged deer, like Micromeryx.

Figure 2. Skulls of the sable antelope, Hippotragus.

Hippotragus niger
(Harris 1838; 190–255cm long) is the extant sable antelope. Here it nests with the much smaller antelope, Matoqua, Fig. 1). Everything is larger in the sable antelope except the otic tubes and orbits.

Figure 3. Subset of the LRT focusing on fossil and extant ungulates. Sus is the living pig. Equus is the modern horese. Ceratotherium is the modern rhinoceros. Tapirus is the modern tapir.

References
Günther A 1880. Proc. Zool. Soc. London 1880: 17.
Harris WC 1838. Athenaeum 535: 71.

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