zoocreation


pronghorns
After the flood



Chad Arment (2023)





Pronghorn, Antilocapra americana (CC BY 2.0 Larry Lamsa)



The pronghorn, Antilocapra americana, is the sole living species in the Family Antilocapridae. Antilocapra comes from the Latin for ‘antelope goat,’ though they are only rudimentally similar to antelopes or goats. Pronghorns are only found in central and western North America, and are colloquially called ‘antelope,’ (as in, “Oh, give me a home, where the buffalo roam, and the deer and the antelope play . . .”) though they are not actual antelopes (which make up several clades within the Family Bovidae). Both the Antilocapridae and Bovidae are included in the Order Artiodactyla, within the Suborder Ruminantia, and within the Infraorder Pecora, but the pronghorns are closer morphologically to the Family Giraffidae, while the bovids nest along with the deer (Cervidae) and musk deer (Moschidae). The Antilocapridae has two subfamilies: the Antilocaprinae (found from Miocene to present day) and the Merycodontinae (Miocene only).


Within a creationist phylogenetic scheme, it is possible that the ruminants make up a single multi-familial baraminic lineage (Lightner 2012). This would necessitate extensive post-Flood diversification. Even if the holobaraminic level for ruminants was generally at the family level, though, there are still a multitude of genera and species in the fossil record. While we only have a single pronghorn species living today, there are twenty genera and numerous species known to have inhabited North America (and only North America) during the post-Flood period, with fossils in deposits from the Miocene to the Holocene. The evolutionary model speculates that an ancestral Eurasian ruminant, identity unknown, arrived over the Bering Strait in the late Oligocene or early Miocene. The creation model would be similar: either an ancestral ruminant or an ancestral antilocaprid (identity unknown either way) arrived in North America from Eurasia. It seems more reasonable that this emigrating ancestor was an earlier ruminant form, simply because there are no antilocaprid fossils in Eurasia, while there are numerous other ruminants (Mennecart et al. 2021).





Seedskadee National Wildlife Refuge, Wyoming (CC BY 2.0 Tom Koerner/USFWS)



As with many other ruminants with elaborate head displays (antlers in deer, horns in antelope, sheep, and cattle), antilocaprids had a diversity of horn formations. In most deer, a male’s antlers (made of bone and covered in ‘velvet’ as they grow) are shed every winter. Bovid horns are not shed, but are a bony horn core covered in a keratinous sheath. Giraffids have ossicones with a bony core covered in skin and keratin. Within the antilocaprids, the Miocene merycodonts had permanent bony horns covered in skin, similar to a deer in velvet. In antilocaprines, most had a keratinous sheath over a bony horn core, just as the living pronghorn does. Most probably shed their horns every year (Marriott and Prothero 2022). While there are similarities between antilocaprid and bovid horncores, homology “is unlikely” (Janis and Manning 1998).


Antilocaprid horns can be variable within a species, so horns alone are not a solid character for designating species or genera. Even modern pronghorns can be variable, with some populations developing ‘four-horned’ phenotypes similar to certain fossil species (Marriott and Prothero 2022).





Pronghorn shed of keratinous sheath (NPS / Jacob W. Frank)



From Scott (1962), reprint of 1937 edition



Osbornoceros



Merriamoceros



Plioceros



Ramoceros



Proantilocapra



Paracosoryx



Ilingoceros



Capromeryx



Ramoceros



Hayoceros



Merycodus



Tetrameryx



A Post-Flood View of the Family Antilocapridae



Merycodonts



Merycodonts are considered more ‘primitive,’ because they appear lower biostratigraphically (back to very early Miocene [Beatty and Martin 2009]) and have some ancestral traits to antilocaprids. They are generally smaller (most only about 20 inches at the shoulder) than antilocaprines, and their bony horns (at least in some species) appear to have been covered in skin which may have been shed and regrown deciduously, leaving bony ring deposits (‘pseudoburrs’) near the base of the horns (Heffelfinger et al. 2002). This likely developed into the keratinized sheath of later antilocaprines. Most retained dew claws, along with upper canine teeth—neither of which are found in antilocaprines. As with later pronghorns, the early merycodonts were cursorial. Some, like Paracosoryx, had teeth indicating shrub browsing, while others like Cosoryx were probably grazers. It is possible that they “browsed or grazed seasonally and regionally” just as the dwarf neotragine antelopes do today (Semprebon and Rivals 2007).


Despite their early appearance in the fossil record, merycodont horns were variable. Several had deer-like characteristics. Ramoceros had very antler-like horns, with three tines on each, but the two horns were asymmetrical, with one much larger than the other. Merriamoceros had somewhat moose-like palmate-cup antlers. Others like Merycodus had more typical tined horns.



Cosoryx furcatus (CC BY 2.0 James St. John)



Paracosoryx loxocerus (Furlong 1934)



Ramoceros osborni (CC BY-SA 2.0 Ryan Somma)



Antilocaprines



The earliest antilocaprines show up during the Miocene before the latest merycodonts disappeared. There are four tribes of antilocaprines, with the Antilocaprini, Ilingoceratini, and Proantilocaprini appearing first in the Miocene, and the Stockoceratini appearing first in the Pliocene. Only the Antilocaprini and Stockoceratini cross into the Pleistocene, though both continue into the Holocene. Only Antilocapra survives today. Modern pronghorns have highly hypsodont (high-crowned) cheek teeth, which often indicates greater reliance on abrasive grasses, but though they occupy prairie grasslands or scrublands, pronghorns are selective feeders and prefer forbs or shrubs where available (Rivals and Semprebon 2006). The hypsodonty may carry over from an abrasive grass-feeding ancestry, or may be selectively supported by grit encroachment from a dry environment.


Some antilocaprines had horns generally similar to modern pronghorns, perhaps with a blunter fork (Sphenophalos) or thicker fork (Ottoceros). The rear fork of Capromeryx was longer and bent forward. Tetrameryx had four straight horns, each sheathed separately, with the rear horns much longer. Hexobelomeryx and Hexameryx each had six horns (or rather a pair of three-tined horns with very short horn shafts, giving that appearance [Janis and Manning 1998]). Ilingoceros had a pair of long, twisting horn cores, so that it looked very antelope-like. Osbornoceros had long, sweeping arches in its horns, so that it looked very bovid-like. Modern pronghorns have two straight bony horn cores, while the keratinous sheath has a distinct prong. This suggests that the antilocaprine ancestor for the modern pronghorn had a bony fork in its horn core (Webb 1973; Heffelfinger et al. 2002). A second species of Antilocapra is known from Pleistocene California, differing in that it had much larger horn cores.



Stockoceros onusrosagris (CC BY 2.0 James St. John)



Capromeryx (Scott 1962)



A comparison of Sphenophalos (top)

and Antilocapra (bottom)

(Barbour and Schultz 1941)



Relevance to Creation Biology



One of the earliest creation papers using biostratigraphy to evaluate potential Flood/post-Flood boundaries was Dr. Marcus Ross’ (2012) examination of 303 genera from 28 North American terrestrial mammal families and their appearance in the fossil record. Using a ‘finer resolution’ approach through North American Land Mammal Ages (NALMA), analysis showed that the high percentage of ‘boundary-crossing’ genera through fossil appearance on both sides of the alleged Pliocene-Pleistocene boundary make that speculative boundary untenable. The paper specifically highlights the Antilocapridae as an endemic North American family with four genera that cross the Irvingtonian-Blancan boundary: Antilocapra, Capromeryx, Stockoceros, and Tetrameryx.


The endemicism of antilocaprids is another key point for the Flood Boundary debate that Ross’ paper notes. Why would the pronghorn family only be found in North America before and after the Flood? The idea that these, and so many other endemic families around the world, would return to the sole continent where their ancestors were buried in Flood deposits, and only to that continent, is absurd. Clearly, the Flood/post-Flood boundary is much lower in the fossil record. The ‘Pliocene-Pleistocene boundary-crossing genera’ simply represent populations in the post-Flood world as global climate change triggered by the Flood is leading to the Ice Age.





Seedskadee National Wildlife Refuge, Wyoming​ (CC BY 2.0 Tom Koerner/USFWS)



references



Barbour, E. H., and C. B. Schultz. 1941. A new species of Sphenophalos from the Upper Ogallala of Nebraska. Bulletin of the University of Nebraska State Museum 2(6): 59-62.


Beatty, B. L., and L. D. Martin. 2009. The earliest North American record of the Antilocapridae (Artiodactyla, Mammalia). PaleoBios 29(1): 29-35.


Furlong, E. L. 1934. New merycodonts from the Upper Miocene of Nevada. Carnegie Institution of Washington Publ. 453, pp. 1-10.


Heffelfinger, J. R., et al. 2002. A bestiary of ancestral antilocaprids. in: Abegglen, J. S., and W. Sue Fairbanks, eds. Proceedings of the 20th Biennial Pronghorn Workshop, pp. 87-111.


Janis, C. M., and E. Manning. 1998. 33 Antilocapridae. in: Janis, C. M., et al., eds. Evolution of Tertiary Mammals of North America. Volume 1: Terrestrial Carnivores, Ungulates, and Ungulatelike Mammals. Cambridge, UK: Cambridge University Press.


Lightner, J. 2012. Mammalian ark kinds. Answers Research Journal 5: 151-204.


Marriott, K. L., and D. R. Prothero. 2022. Variability of the horns of pronghorns (Mammalia: Artiodactyla: Antilocapridae): Implications for pronghorn systematics. Fossil Record 8. New Mexico Museum of Natural History and Science Bulletin 89: 289-293.


Mennecart, B., et al. 2021. Ruminants reveal Eocene Asiatic palaeobiogeographical provinces as the origin of diachronous mammalian Oligocene dispersals into Europe. Scientific Reports 11: 17710.


Rivals, F., and G. M. Semprebon. 2006. A comparison of the dental habits of a large sample of the Pleistocene pronghorn Stockoceros onusrosagris from the Papago Springs Cave in Arizona to the modern Antilocapra americana. Journal of Vertebrate Paleontology 26(2): 495-500.


Ross, M. R. 2012. Evaluating potential post-Flood boundaries with biostratigraphy—the Pliocene/Pleistocene boundary. Journal of Creation 26(2): 82-87. [PDF]


Scott, W. B. 1962. A History of Land Mammals in the Western Hemisphere. Revised Edition. New York: Hafner.


Semprebon, G. M., and F. Rivals. 2007. Was grass more prevalent in the pronghorn past? An assessment of the dietary adaptations of Miocene to Recent Antilocapridae (Mammalia: Artiodactyla). Palaeogeography, Palaeoclimatology, Palaeoecology 253: 332-347.


Webb, S. D. 1973. Pliocene pronghorns of Florida. Journal of Mammalogy 54(1): 203-221.


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zoocreation