“Creodonts”: Carnivores by Association:
[Via Catalogue of Organisms]
“Karianne’s Pet” by Carl Buell. The large animal in the painting is the hyaenodontid Megistotherium osteothlastes, a contender for the title of biggest carnivorous mammal ever.
As explained in an earlier post (which you may be interested in reading as a bit of background to this one), the earlier part of the Caenozoic (the current era of the earth’s history) was home to a number of mammalian lineages of very mysterious relationships. Very few of the familiar orders around us today had yet put in an appearance, and instead the world was home to such oddities as pantodonts, tillodonts and dinocerates. Among the prominent carnivorous mammals of the time were a group known as the creodonts. Creodonts ranged in size from that of a small cat to lion- or bear-size species, and often converged in appearance with those animals. But what were creodonts?
Current authors regard the Creodonta as including two families, the vaguely cat-like Oxyaenidae and the largely dog- or hyaena-like Hyaenodontidae. Oxyaenids were found in North America and Europe during the late Palaeocene and Eocene, while hyaenodontids were found in Africa, Eurasia and North America from the Late Palaeocene to near the end of the Miocene, though they disappeared from North America not long after the end of the Eocene (Gheerbrant et al., 2006). Many authors have suggested a relationship with modern carnivorans (cats, dogs, weasels, bears, etc.), and they have been included with the latter in a superorder Ferae. Popular as this arrangement has been, however, there’s just one small problem – there’s not a shred of evidence to support it.
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A wonderful post demonstrating why taxonomy at lower levels and biological systematics at higher levels can be so troublesome. we just do not have enough information about some extinct species to make an accurate call.
And his explanation for taxonomic drift is excellent and why taxonomy requires a tremendous depth of knowledge in order to keep things straight. Because even though researchers may be using the same names, they may be describing separate species.
It does make me wish some creodonts survived. Wouldn’t it be nice to have one as a pet?
But I love this site. It describes the results of taxonomic drift thusly:
Eventually, the creodonts were whittled down to their modern content of oxyaenids and hyaenodontids, but, as pointed out by Polly (1996), “Hyaenodontidae and Oxyaenidae are currently grouped together in Creodonta because they are the only taxa that have not been removed from the group, not because there has been specific positive evidence proposed for their grouping”.
[snip]The only real reason creodonts have been associated with Carnivora for so long seems to be their prior inclusion of the genuinely carnivoran (or stem-carnivoran) miacids. It’s a bit like when one of your friends brings an acquaintance of theirs to a party who just hangs around for hours with everybody being too polite to ask them to leave.
So the group stays with carnivores only for historical reasons, not for any real reason of relatedness. Sounds like an area ripe for new investigations. I wonder if any DNA can been recovered from creodont fossils? Probably too old.
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