Schowalteria is a genus of extinct mammal from the Cretaceous of Canada. It is the earliest known representative of Taeniodonta, a specialised lineage of non-placental eutherian mammals otherwise found in Paleocene and Eocene deposits. It is notable for its large size, being among the largest of Mesozoic mammals, as well as its speciation towards herbivory, which in some respects exceeds that of its later relatives.
R. C. Fox and B. G. Naylor. 2003
Currently, Schowalteria is considered to be a monotypic genus, with only one species, S. clemensi. It is known from only one skull. Schowalteria shares some speciations with later taeniodonts, namely similar canine and incisor morphology, similar facial proportions and zygomatic arch construction, though unlike them its occlusal surface is worn nearly completely flat, and the wear facet completely encompasses the paracone and metacone, leaving only an outline of the buccal side of the bases of these cusps remaining, differing radically from the more "normal" teeth wearing patterns of other taenidonts. Based on the skull's proportions, it was initially comparared in size to Didelphodon vorax, making it one of the largest mammals of the Mesozoic at the time of its discovery, and posterior measurements have cited larger sizes; Anne Weil posits a range similar (though not confirmed) to Repenomamus giganticus, while posterior analysis showcase it to be as large as latter taeniodonts.
Schowalteria occurs in the Trochu deposits of Alberta, dating to the Maastrichtian stage of the Cretaceous period. This site is part of the larger Edmonton Group, that probably represented a warm, temperate environment. Mammal remains are very common in this site, such as various metatherians and multituberculates.
Schowalteria is a taeniodont eutherian. It was initially recovered as a fairly derived member related to stylinodonts, but more recent examinations show it to be a more basal species within the group, less related to them than Onychodectes.
In spite of being a basal taeniodont, Schowalteria is fairly derived, perhaps more so than later taenidonts. It shares with them similar speciations towards herbivory and possibly fossoriality, but unlike them it also possesses evidence of transverse (ungulate-like) mastication, making it even more specialised towards processing vegetation.
As one of the largest mammals of its time period and a rather specialised herbivore, Schowalteria was a rather spectacular species among the dinosaur-rich faunas of the end of the Cretaceous.
Aegialodon dawsoni is an extinct mammal from the early Cretaceous, known from fossilised teeth discovered in the Wadhurst Clay Formation (dating to about 136 million years ago) near Cliff End, Hastings, East Sussex.Alphadontidae
Alphadontidae was a family of small, primitive mammal that was a member of the metatherians, a group of mammals that includes modern-day marsupials.Aploconodon
Aploconodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.
Present in stratigraphic zone 5.Barylambdidae
Barylambdidae is an extinct family of pantodont mammals from North America.Cladotheria
Cladotheria is a group (legion) of mammals that includes the ancestor of Dryolestoidea, Peramuridae and Zatheria (living therians plus all of its ancestors).Comodon
Comodon is an extinct genus of Late Jurassic mammal from the Morrison Formation.
Present in stratigraphic zone 5.Deltatheroides
Deltatheroides is an extinct genus of Deltatheridiidae from Cretaceous of Mongolia.Hakusanobaatar
Hakusanobaatar is an extinct genus of eobaatarid multituberculate which existed in Japan, during the early Cretaceous.Henosferidae
Henosferidae (also spelled "Henospheridae") is an extinct family of Australosphenida. Its defined as a clade including the most recent common ancestor of Henosferus and Asfaltomylos and all its descendants.Kollikodon
Kollikodon ritchiei is a australosphenidan species, often classified as a monotreme but more recently recovered as an outgroup. It is known only from an opalised dentary fragment, with one premolar and two molars in situ. The fossil was found in the Griman Creek Formation at Lightning Ridge, New South Wales, Australia, as was Steropodon.
Kollikodon lived in the lower Cretaceous period, during the middle Albian age (113-101 million years ago).
Like Steropodon, Kollikodon was a relatively large mammal for the Mesozoic. The molars have a length of around 5.5 mm and a width of between about 4 and 6 mm (Clemens et al., 2003). Based upon these data, the potential body length could be up to a metre. Assuming the accuracy of such a guess, Kollikodon would be a contender for the largest Mesozoic mammal known, along with other possible giants such as Repenomamus, Schowalteria, and Bubodens.
Aside from its size, it is difficult to say what Kollikodon looked like. It is certain that its teeth were specialised to crush food, being perhaps a shellfish-eater or herbivore.
Both Kollikodon and Steropodon can be found at the Australian Museum in Sydney, along with Eric, the opalised pliosaur.Leptolambda
Leptolambda is an extinct genus of pantodonts in the family Barylambdidae from North America.Oklatheridium
Oklatheridium is an extinct genus of deltatheroidan.Palaeosinopa
Palaeosinopa is an extinct genus of semi-aquatic, non-placental eutherian mammals belonging to the family Pantolestidae. Their diet consisted of other semi-aquatic life forms.Paressonodon
Paressonodon is an extinct genus of multituberculate which existed in Colorado during the late Cretaceous period. It contains the species Paressonodon nelsoni.Plethorodon
Plethorodon is an extinct genus of tillodont that lived during Early to Late Paleocene. The type species is P. qianshanensis. which known from partial skull and upper teeth that had been discovered by Huang and Zheng at 1987 at Qianshan, Anhui Province, China.Presbytherium
Presbytherium is an extinct pantodont which existed in what is now Alberta, Canada, during the Paleocene period. It was first named by Craig S. Scott in 2010.Taeniodonta
Taeniodonta ("banded teeth") is an extinct early group of cimolestid mammals known from the Palaeocene to the Eocene. Taeniodonts evolved quickly into highly specialized digging animals, and varied greatly in size, from rat-sized to species as large as a bear. Later species developed prominent front teeth and huge claws for digging and rooting. Some genera, like Stylinodon, had ever-growing teeth.Two families belong to this group, Stylinodontidae and Conoryctidae. They were endemic to North America. The scarcity of taeniodont fossils can be explained by the fact that these animals probably lived in dry or arid climates unconductive to fossilization. Taeniodonts are unambiguously Eutherians, and part of Cimolesta; Cimolestes is the immediate outgroup to Taeniodonta.Tathiodon
Tathiodon is an extinct genus of Late Jurassic (Kimmeridgian - Tithonian) mammal from the Morrison Formation.
Present in stratigraphic zone 5.