Megalictis ferox

Megalictis ferox Temporal range: Miocene
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Mustelidae
Subfamily:	Oligobuninae
Genus:	Megalictis
Species:	M. ferox
Binomial name
Megalictis ferox Matthew, 1907

Megalictis ferox was a species of large predatory mustelid, now extinct, which existed in North America during the "cat gap" in the Miocene period. It is thought to have resembled a large wolverine, with a body mass of up to 60 kg.

Species identification

The genus Megalictis was first described by W. D. Matthew in 1907, and assigned to the family Mustelidae.^[1] Two similar genera discovered at the same time, Aelurocyon (Peterson, 1907) and Paroligobunis (Peterson, 1910) were identified as synonymous with Megalictis in 1996.^[2] P. R. Bjork, in 1970, assigned the genus to the subfamily Mellivorinae,^[3] whilst J. A. Baskin reassigned it to Oligobuninae in 1998.^[1] Two other species have been identified in the genus: Megalictis petersoni and Megalictis frazieri, whilst two more, Megalictis brevifacies and Megalictis simplicidens, have since been determined to be synonymous with Megalictis ferox. Other synonyms for the species include Aelurocyon brevifacies, Brachypsalis simplicidens and Paroligobunis simplicidens.^[1]

Specimens of the species have been found at ten sites in South Dakota, Nebraska and Wyoming, dated to the Harrisonian period - from 24.8 to 20.6 million years ago.^[1] The 19 specimens so far identified have a wide range of sizes,^[2] which is believed to be evidence of extreme sexual dimorphism, a phenomenon where males and females of the species will grow to different sizes; a 1996 study rejected the possibility of multiple "morphologically uniform" but differently sized species as unlikely.^[4] However, later studies identified significant morphological variation in the joints of the forearms, which would not be consistent with sexual dimorphism. suggests that the identification of all of these as a single species may need revision.^[5]

Physiology

Some writers suggest it could grow to the size of a black bear,^[6] whilst others suggest a less exceptional mass of 20-60 kg, compared to the wolverine of 10-20 kg. Ekorus ekakeran, a comparable mustelid of the same period found in Africa, is estimated to have been around 40 kg.^[2] Matthew described it as having short stout legs, with short feet and long non-retractible claws, similar to a modern wolverine but about twice the size,^[2] and noted that "the teeth indicate an animal fully as predaceous as the wolverine, but the skeleton points to more fossorial habits".^[7] Research comparing the joints of the forelegs to modern mammalian carnivores suggests that it waited in ambush and grappled with its prey, rather than hunting it down by pursuit like a modern cheetah.^[8]

Notes

1. ^ ^{a b c d} Paleobiology Database
2. ^ ^{a b c d} Andersson, p.39
3. ^ Bjork, p.18
4. ^ Hunt & Skolnick, quoted Andersson, p.39-40
5. ^ Andersson, p.11 & p.40
6. ^ Allaby, "Mustelidae"
7. ^ Quoted in Gratacap, p.921
8. ^ Hopkin

References

• Allaby, Michael, ed (1999). A Dictionary of Zoology. Oxford: Oxford University Press. 
• Andersson, Ki (2003). Locomotor evolution in the Carnivora (Mammalia): evidence from the elbow joint. http://www.carnivoreconservation.org/files/thesis/anderson_2003_msc.pdf. 
• Bjork, Philip Reese (1970). "The Carnivora of the Hagerman Local Fauna (Late Pliocene) of Southwestern Idaho". Transactions of the American Philosophical Society 60 (7). 
• Gratacap, L. P. (June 12, 1908). "Scientific Publications of the American Museum of Natural History for 1907". Science 27 (702): 920. doi:10.1126/science.27.702.920. 
• Hopkin, Michael (30 September 2004). "Research highlights: elbow room for top predators". Nature 431 (7008): 524. doi:10.1038/431524a. 
• "The giant mustelid Megalictis from the Early Miocene carnivore dens at Agate Fossil Beds National Monument, earliest evidence of dimorphism in New World Mustelidae". Contributions to Geology (31): 35–48. 1996. 
• "Megalictis ferox at the Paleobiology Database.". paleodb.org. http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=48009&is_real_user=0. Retrieved 2008-11-25.