''Cifelliodon'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

mammaliaform Mammaliaformes ("mammalian forms") is a clade that contains the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts. It is defined as the clade originating from the most recent comm ...

s from the

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eig ...

of North America. In the describing paper, it was considered one of the latest surviving haramiyids yet known, belonging to the family

Hahnodontidae Hahnodontidae is a family of extinct mammaliaforms from Early Cretaceous deposits in Morocco and the Western United States. Although originally considered to belong to the extinct clade Multituberculata, recent work indicates that hahnodontids ...

. Its discovery led to the proposal to remove hahnodontids from the larger well-known group, the

multituberculates Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, a ...

. However, later papers have considered it to be a basal allotherian outside of Haramiyida. The sole species in the genus, ''Cifelliodon wahkarmoosuch'', was found in the geological rock unit called the Yellow Cat Member, part of the

Cedar Mountain Formation The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid- Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where Will ...

in Grand County,

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

. This rock unit dates to between 139-124 million years old. It was found alongside the remains of several dinosaurs - a large

iguanodon ''Iguanodon'' ( ; meaning ' iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species have been classified in the genus ''Iguanodon'', dating from the late Jurassic Period to the early Cretaceous Period of Asia, ...

tian, a

dromaeosaur Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...

, and an

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous wo ...

- and parts of a

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

Etymology

The genus name, ''Cifelliodon'', means Cifelli's tooth, and honours the well-known mammal palaeontologist,

Richard Cifelli Richard is a male given name. It originates, via Old French, from Old Frankish and is a compound of the words descending from Proto-Germanic ''*rīk-'' 'ruler, leader, king' and ''*hardu-'' 'strong, brave, hardy', and it therefore means 'stron ...

. The species name, ''C. wahkarmoosuch'' comes from the

Ute language Ute Givón, T. ''Ute Reference Grammar''. John Benjamins Publishing Company, 2011 is a dialect of the Colorado River Numic language, spoken by the Ute people. Speakers primarily live on three reservations: Uintah-Ouray (or Northern Ute) in nort ...

, and means yellow (wahkar) cat (moosuch).

Description

The holotype of ''Cifelliodon wahkarmoosuch'' is an exceptionally well-preserved skull, housed at the Natural History Museum of Utah. The skull measures 70 mm in length, giving an estimated body mass of 0.91-1.27 kg. The skull is broad and shallow with a reduced tooth count. There is a prominent sagittal crest. Inside the skull on each side are two incisors, a canine, and four postcanines, all of them broken off at the gumline except for the last molars. These last molars had not yet erupted, and so their intact crowns allowed palaeontologists to identify this mammaliaform. The preserved skull allowed palaeontologists to see the brain size of ''Cifelliodon'', and they concluded it was a transitional size and shape between earlier stem mammals, and crown mammals. It appears to have had a well-developed sense of smell, as did most mammals in the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

Phylogeny

Previously, scientists had suggested that the hahnodontids belonged to the well-known group of mammals called

. However, examining the anatomy of ''Cifelliodon'', Huttenlocker et al. (2018) found it to be closely related to '' Hahnodon'', and placed them outside of Multituberculata and outside the crown mammals. This makes hahnodontids a late surviving stem mammal group. It also suggests that there were greater links between the tetrapod animals across the continents in the Cretaceous. Krause ''et al.'' (2020) recovered ''Cifelliodon'' as a basal member of

Allotheria Allotheria (meaning "other beasts", from the Greek , '–other and , '–wild animal) is an extinct branch of successful Mesozoic mammals. The most important characteristic was the presence of lower molariform teeth equipped with two longitudin ...

, outside of the clade containing

Euharamiyida Euharamiyida also known as Eleutherodontida, is clade of early mammals or mammal-like cynodonts from the Middle Jurassic to Early Cretaceous of Eurasia and possibly North America. The group is sometimes considered a sister group to Multitubercula ...

and 'Multituberculata +

Gondwanatheria Gondwanatheria is an extinct group of mammaliaforms that lived in parts of Gondwana, including Madagascar, India, South America, Africa and Antarctica during the Upper Cretaceous through the Paleogene (and possibly much earlier, if '' Allostaff ...

'. Their analysis did not include ''Hahnodon''.

References

{{Taxonbar, from=Q55391290 Haramiyida Prehistoric cynodont genera Early Cretaceous synapsids of North America Fossil taxa described in 2018 Taxa named by Adam K. Huttenlocker Taxa named by David M. Grossnickle Taxa named by James I. Kirkland Taxa named by Julia A. Schultz Taxa named by Zhe-Xi Luo