New Utah fos­sil

Serve Daily - - NEWS - By Nathan Sch­we­bach Utah De­part­ment of Nat­u­ral Re­sources

A small fos­sil is ev­i­dence that Earth’s an­cient su­per­con­ti­nent, Pangea, separated some 15 mil­lion years later than pre­vi­ously be­lieved.

A nearly 130-mil­lion-year-old fos­silized skull found in Utah is an Earth-shat­ter­ing dis­cov­ery in one re­spect.

The small fos­sil is ev­i­dence that the su­per-con­ti­nen­tal split likely oc­curred more re­cently than sci­en­tists pre­vi­ously thought and that a group of rep­tile-like mam­mals that bridge the rep­tile and mam­mal tran­si­tion ex­pe­ri­enced an un­sus­pected burst of evo­lu­tion across sev­eral con­ti­nents.

“Based on the un­likely dis­cov­ery of this near-com­plete fos­sil cra­nium, we now rec­og­nize a new, cos­mopoli­tan group of early mam­mal rel­a­tives,” said Adam Hut­ten­locker, lead au­thor of the study and as­sis­tant pro­fes­sor of clin­i­cal in­te­gra­tive anatom­i­cal sci­ences at the Keck School of Medicine of USC.

The study, pub­lished in the journal Na­ture on May 16, up­dates the un­der­stand­ing of how mam­mals evolved and dis­persed across ma­jor con­ti­nents dur­ing the age of di­nosaurs. It sug­gests that the di­vide of the an­cient land­mass Pangea con­tin­ued for about 15 mil­lion years later than pre­vi­ously thought and that mam­mal mi­gra­tion and that of their close rel­a­tives con­tin­ued dur­ing the Early Cre­ta­ceous (145 to 101 mil­lion years ago).

“For a long time, we thought early mam­mals from the Cre­ta­ceous (145 to 66 mil­lion years ago) were anatom­i­cally sim­i­lar and not eco­log­i­cally di­verse,” Hut­ten­locker said. “This find­ing by our team and oth­ers re­in­force that, even be­fore the rise of mod­ern mam­mals, an­cient rel­a­tives of mam­mals were ex­plor­ing spe­cialty niches: in­sec­ti­vores, her­bi­vores, car­ni­vores, swim­mers, glid­ers. Ba­si­cally, they were oc­cu­py­ing a va­ri­ety of niches that we see them oc­cupy to­day.”

The study re­veals that the early mam­mal pre­cur­sors mi­grated from Asia to Europe, into North Amer­ica and fur­ther onto ma­jor South­ern con­ti­nents, said Zhe-Xi Luo, se­nior au­thor of the study and a pa­le­on­tol­o­gist at the Uni­ver­sity of Chicago. Fos­sil find: a new species Hut­ten­locker and his col­lab­o­ra­tors at the Utah Ge­o­log­i­cal Sur­vey and The Uni­ver­sity of Chicago named the new species Cifel­liodon wahkar­moosuch.

Found in the Cre­ta­ceous beds in eastern Utah, the fos­sil is named in honor of famed pa­le­on­tol­o­gist Richard Cifelli. The species name, “wahkar­moosuch” means “yel­low cat” in the Ute tribe’s lan­guage in re­spect of the area where it was found.

Sci­en­tists used high-res­o­lu­tion com­puted to­mog­ra­phy (CT) scan­ners to an­a­lyze the skull.

“The skull of Cifel­liodon is an ex­tremely rare find in a vast fos­sil-bear­ing re­gion of the Western In­te­rior, where the more than 150 species of mam­mals and rep­tile-like mam­mal pre­cur­sors are rep­re­sented mostly by iso­lated teeth and jaws,” said James Kirk­land, study co-au­thor in charge of the ex­ca­va­tion and a Utah State pa­le­on­tol­o­gist.

With an es­ti­mated body weight of up to 2.5 pounds, Cifel­liodon would seem small com­pared to many liv­ing mam­mals, but it was a giant among its Cre­ta­ceous con­tem­po­raries. A full-grown Cifel­liodon was prob­a­bly about the size of a small hare or pika (small mam­mal with rounded ears, short limbs and a very small tail).

It had teeth sim­i­lar to fruit-eat­ing bats and could nip, shear and crush. It might have in­cor­po­rated plants into its diet.

The newly named species had a rel­a­tively small brain and giant “ol­fac­tory bulbs” to process sense of smell. The skull had tiny eye sock­ets, so the animal prob­a­bly did not have good eye­sight or color vi­sion. It pos­si­bly was noc­tur­nal and de­pended on sense of smell to root out food, Hut­ten­locker said.

Su­per­con­ti­nent ex­isted longer than pre­vi­ously thought Hut­ten­locker and his col­leagues placed Cifel­liodon within a group called Haramiyida, an ex­tinct branch of mam­mal an­ces­tors re­lated to true mam­mals. The fos­sil was the first of its par­tic­u­lar sub­group – Hahn­odon­ti­dae – found in North Amer­ica.

The fos­sil dis­cov­ery em­pha­sizes that haramiyi­dans and some other ver­te­brate groups ex­isted glob­ally dur­ing the Juras­sic-Cre­ta­ceous tran­si­tion, mean­ing the cor­ri­dors for mi­gra­tion via Pangean land­masses re­mained in­tact into the Early Cre­ta­ceous.

Most of the Juras­sic and Cre­ta­ceous fos­sils of haramiyi­dans are from the Tri­as­sic and Juras­sic of Europe, Green­land and Asia. Hahn­odon­ti­dae was pre­vi­ously known only from the Cre­ta­ceous of North­ern Africa. It is to this group that Hut­ten­locker ar­gues Cifel­liodon be­longs, pro­vid­ing ev­i­dence of mi­gra­tion routes be­tween the con­ti­nents that are now separated in north­ern and south­ern hemi­spheres.

“But it’s not just this group of haramiyi­dans,” Hut­ten­locker said. “The con­nec­tion we dis­cov­ered mirrors oth­ers rec­og­nized as re­cently as this year based on sim­i­lar Cre­ta­ceous di­nosaur fos­sils found in Africa and Europe.”

Photo: Utah De­part­ment of Nat­u­ral Re­sourcesC

Views of the skull of Cifel­liodon, a new di­nosaur species.

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