During the middle Eocene, about 49 to 37 million years ago, the largest meat-eating mammal from what would become of the Wind River Formation of Wyoming was Malfelis badwaterensis. Although a cursory glance at the fossil remains of this animal might suggest it was related to dogs or cats (which are living carnivorans), Malfelis was actually a creodont, belonging to an extinct group of meat-eating mammals that may have shared a common ancestor with the carnivorans (see the comment by johannes below). Although people who are not actively engrossed in paleontology rarely ever hear about them, creodonts were among the most important of North American predators from the middle Paleocene to the late Oligocene (about 62 million years ago to about 23 million years ago). They are also known from Asia, Europe, and Africa, but it is the North American creodonts that have often received the most attention.
Malfelis is the latest addition to the ranks of North American creodonts, and the most telling features of this extinct predator are the teeth. The skull that was recovered was actually from a juvenile animal, as it still had some deciduous (or "milk") teeth when it died. Of these teeth, the premolars are the most suggestive of diet. In carnivorous mammals, the premolars and molars often form what is known as a "carnissal shear," the teeth working in a scissor-like slicing fashion. Creodonts, like living carnivorans, exhibit this feature, but in some creodonts the premolars had a more robust form that aided them in crushing bones. Malfelis lacks such adaptation, the premolars showing no sign that they were used to crack open bones. Malfelis also had two molars, but the second one was so small that the authors of the paper describing it thought that it is probably vestigial. This feature most closely allies Malfelis to the oxyaenids, a particular sub-group of creodonts.
Overall, the skull of Malfelis was relatively long and narrow, the premolars being much less robust than in other creodonts thought of as bone-crushers. It should be kept in mind that the canines and premolars of the specimen were deciduous and may have differed somewhat in the adult, although the overall form of the skull suggests that Malfelis was a pursuit predator. Interestingly enough, with the juvenile skull being just under a foot long, Malfelis was among the largest mammals recovered from the Wind River Formation in which it was found. No postcranial material has been discovered as yet, nor did the authors provide a listing of the approximately 80 mammal species found in the formation, but the described remains of Malfelis still would have made it a top predator in its environment.
The creodonts Patriofelis and Protopsalis are also known from the same formation, and all three genera may have preyed upon creatures such as titanotheres, ancient
rhinoceroses and tapirs, and uintatheres. Being that Patriofelis was likely a bone-crusher, the more gracile features of Malfelis may be a reflection of a common pattern among carnivores where predators become adapted to have more specific prey preferences and hunting/flesh acquisition strategies. Given the amount of material that seems to be known from this site, a taphonomic study might be warranted to see if inferences about the habits of these creodonts are supported.
References;
Stucky, R.K.; Hardy, T.G. (2007) "A New Large, Hypercarnivorous Oxyaenid (Mammalia, Creodonta) From the Middle Eocene of the Wind River Formation, Natrona County, Wyoming." Bulletin of the Carnegie Museum of Natural History, No. 39, pp. 57 - 65
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Thanks! When I was a small child, oxyaenids were almost everywhere - every classroom in every elementary school in Germany had a roll out poster showing the different ages of earth history, illustrated in a Zdenek Burian style that was obsolete even back then, but never the less alluring in an antique, nostalgic way. The Tertiary section invariably included an oxyaenid, usually *Patriofelis*. The elementary school teacher invariably told the kids that this was the ancestor of cats (argh)...
Ditto for popular books on extinct animals up to the eighties: There always was a picture of an oxyaenid, accompanied by a text that said they were ambush predators, and therefore went extinct when the climate got cooler, drier and more seasonal, and jungle was replaced by savannah - well, this proves why cats never evolved :-).
But somehow oxyaenids became forgotten since then. Even as impressive a monster as *Sarkastodon* failed to capture the public's imagination. Thanks for bringing them back to the limelight again!
> Malfelis was actually a creodont, belonging to an
> extinct group of meat-eating mammals that likely shared
> a common ancestor with the carnivorans
Caution should be advised here! Nobody seems to know for sure if hyaenodonts and oxyaenids even formed a common clade, leave alone if this clade is the sister group of carnivorans. We are in dire need of a proper cladistic analysis of the creodonts, and the result might be that the hyaenodonts are actually afrotheres and the oxyaenids are glorified cimolestans (and therefore not even placentals), or who knows what.
> Malfelis also had two molars
There goes my wisdom from The Velvet Claw that creodonts had no molars (this said, both the book and the TV series are still among the best of their kind)
> the overall form of the skull suggests that Malfelis was a pursuit predator
immediatly followed by the "oxyaenids were ambush predators" meme.
johannes; Thanks for the comment and the corrections/word of caution. I had never heard of creodonts until I started wading through the literature, although I had apparently seen their skeletons a few times before.
As far as the molar question goes, I think TVC is out of date. The molars are explicitly mentioned in the paper, especially the minute character of the 2nd molar.
Yep. The oxyaenids and the hyaenodontids are simply what remains in Creodonta after everything else (mesonychians etc.) had been taken out. As far as I know, no oxyaenid or hyaenodontid has ever been entered into a phylogenetic analysis, and there is no analysis of placental phylogeny that has (for placentals) less cursory taxon sampling than the Maelestes paper. Would make a nice Ph.D. thesis... for someone.
"The Rise of Placental Mammals" (ed. Kenneth Rose and J. Archibald) has a chapter on what is known and what can be surmised about the genealogy of Creodonts and Carnivora. (Chapter by two people, I think one of them is Wyss.) As I recall they found little evidence for a monophyletic Creodonta, but seemed moderately optimistic about a Ferae within which there would be, perhaps, an unresolved trichotomy of Hyaenodontidae, Oxyaenidae and Carnivoramorpha (=Carnivora and a mess of Viveravid and Miacid near-Carnivora*).
One of the fairly few morphological traits usually cited to support the Carnivora (and to unite it with what may be its nearest extant relative, the Pholidota!) is the "osseous tentorium." I recall being a bit frustrated when I last read the chapter that it didn't have an explicit statement of whether or not this has been observed in Creodont skulls.
(*) That is, twigs branching off from the Carnivoran branch below the l.c.a. of extant Carnivora but definitely after it split from the Creodont branch or branches. "Carnivora" is the node-based clade l.c.a. of extant Carnivora and its descendents, "Carnivoramorpha" the clade of everything more closely related to Carnivora than to Creodonts.
Sorry, I was posting from the office yesterday and the library copy of the book was at home: "The Rise of PlacentalMammals," ed. Kenneth D. Rose and J. David Archibald (Johns Hopkins University Press, 2005). The Carnivora chapter is by John J. Flynn and Gina D. Wesley-Hunt (they cite a lot of work by Wyss, who had a hand in the Glires chapterr of the book). The book is meant to be a review of the current state of knowledge, emphasizing the morphological side -- there is one chapter on molecular stuff, and the idea of a close relationship between Perissodactyla and Paenungulata is given a more sympathetic hearing than it would be by convinced Afrotheria-believers. Anyway,as a review, the chapters seem to have good bibliographies of recent work.
I ***DID*** remember JJF and GDW-H's preferred tree correctly. They say that Gunnell (Creodonta chapter of the Janis, Scott & Jacobs "Evolution of Tertiary Mammals of North America" volume) mentioned "defining" features of Creodonta, but opine that neither Gunnell nor Polly (JVP 16 (1996) pp. 303-319) provide "convincing" evidence for Creodont monophyly, and so "conservatively" opt for a tree showing a Hyaenodont/ Oxyaenid/ Carnivoramorph trichotomy.
They do say that Carnivora and Pholidota share the osseous tentorium with Creodonts, but don't go into details (like: is the o.t. well-evidenced both for Oxys and H-donts?). Since the o.t. is an internal cranial feature with no obvious functional significance, it seems (a priori) unlikely to be convergent, so I find it very convincing as evidence for a close relationship between Creodonts and Carnivorans.
> As far as the molar question goes, I think TVC is out of date.
Or perhaps there was a problem with the dubbing: No grinding (as opposed to shearing) molars became no molars at all in the German version.
Malfelis are not true Felines(Cats). It is related to Whales and Dolphins, as well as Pigs! At the time Malfelis has roamed wilderness, ancestors of Felines(Cats) was small weasal like creatures. Therefore Malfelis belong to Creodonta not Carnivora(Order that include Cats and Dogs).