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Fossils of tiny, unknown hedgehog found

Fossils of tiny, unknown hedgehog found

Meet per­haps the ti­ni­est hedge­hog spe­cies ev­er: Sil­va­cola acares. Its roughly 52-mil­lion-year-old fos­sils were iden­ti­fied by re­search­ers in­ves­ti­gat­ing a “lost world” of fos­sil­ized for­est in Can­a­da.

The hedge­hog's sci­en­tif­ic name means “ti­ny for­est dweller,” said Jae­lyn Eberle of the Uni­vers­ity of Col­o­rad­o Boul­der, lead au­thor of the stu­dy. The crea­ture was only about two inches long, roughly the length of an adult thumb.

It is “com­pa­ra­ble in size to some of to­day's shrews,” Eberle said. She spec­u­lat­ed Sil­va­cola may have fed on in­sects, plants and per­haps seeds. Did it have quills like mod­ern hedge­hogs? “We can't say for sure,” Eberle said. “But there are an­ces­tral hedge­hogs liv­ing in Eu­rope about the same time that had bristly hair cov­er­ing them, so it is plau­si­ble Sil­va­cola did too.”

Hedge­hogs have be­come quite the rage as pets in North Amer­i­ca in the past sev­eral years. The most com­mon hedge­hog pet to­day is the Af­ri­can pyg­my hedge­hog, which is up to four times the length of the di­min­u­tive Sil­va­cola.

The fos­sils of the hedge­hog, along with fos­sils of a ta­pir-like mam­mal about the size of a me­di­um-sized dog, were found in north-central Brit­ish Co­lum­bia at a site known as Drift­wood Can­yon Pro­vin­cial Park that likely was a rainfor­est en­vi­ron­ment dur­ing the Early Eo­cene Ep­och about 52 mil­lion years ago, she said.

While the Earth has ex­pe­ri­enced many dra­mat­ic changes in cli­mate since the di­no­saurs died out 66 mil­lion years ago, the Early Eo­cene was one of the warmest pe­ri­ods on Earth since the ex­tinc­tion. Dur­ing this interval-a­bout 53 mil­lion to 50 mil­lion years ago-North Amer­i­can mam­mal com­mun­i­ties were quite dis­tinct from those of to­day, said Eberle.

A pa­per on the dis­cov­ery of the an­cient hedge­hog and ta­pir is be­ing pub­lished to­day in the Jour­nal of Ver­te­brate Pa­le­on­tol­ogy.

“Within Can­a­da, the only oth­er fos­sil lo­cal­i­ties yield­ing mam­mals of si­m­i­lar age are from the Arc­tic, so these fos­sils from Brit­ish Co­lum­bia help fill a sig­nif­i­cant ge­o­graph­ic gap,” said  Re­search Sci­ent­ist Na­tal­ia Ry­bczyn­ski of the Ca­na­di­an Mu­se­um of Na­ture in Ot­ta­wa, On­tar­i­o, a co-au­thor of the stu­dy.

Oth­er fos­sils of the same age have pre­vi­ously been dis­cov­ered in Wy­o­ming and Col­o­rad­o, she said. Mod­ern hedge­hogs and their rel­a­tives are re­strict­ed to Eu­rope, Asia and Af­ri­ca. The ti­ny hedge­hog's del­i­cate up­per teeth were scanned with­out be­ing re­moved from the sur­round­ing rock us­ing an in­dus­t­ri­al, high-resolution scan­ner at Penn State Uni­vers­ity.

The oth­er mam­mal dis­cov­ered at the site, Hep­todon, is an an­cient rel­a­tive of mod­ern ta­pirs, which re­sem­ble small rhi­nos with no horns and a short, mo­bile trunk or pro­bos­cis, said Eberle, al­so cu­ra­tor for ver­te­brate pa­le­on­tol­ogy at the Uni­vers­ity of Col­o­rad­o Mu­se­um of Na­ture and Sci­ence.

Hep­todon was about half the size of to­day's ta­pirs, and it lacked the short trunk that oc­curs on lat­er spe­cies and their liv­ing cous­ins,” said Eberle. “Based up­on its teeth, it was probably a leaf-eater, which fits nicely with the rainfor­est en­vi­ron­ment in­di­cat­ed by the fos­sil plants at the site.”

Most of the fos­sil-bearing rocks at Drift­wood Can­yon were formed on the bot­tom of an an­cient lake and are well known for their ex­cep­tion­ally well-pre­served leaves, in­sects, and fish­es. But no fos­sils of mam­mals had ev­er be­fore been iden­ti­fied at the site.

“The dis­cov­ery in north­ern Brit­ish Co­lum­bia of an early cous­in to ta­pirs is in­tri­guing be­cause to­day's ta­pirs live in the trop­ics,” said Eberle. “Its oc­cur­rence, alongside a di­vers­ity of fos­sil plants that in­di­cates a rainfor­est, sup­ports an idea put for­ward by oth­ers that ta­pirs and their ex­tinct kin are good in­di­ca­tors of dense for­ests and high pre­cipita­t­ion.”

Fos­sil plants from the site in­di­cate the ar­ea sel­dom ex­pe­ri­enced freez­ing tem­per­a­tures and probably had a cli­mate si­m­i­lar to that of con­tem­po­rary Port­land, Ore., roughly 700 miles to the south.

“Drift­wood Can­yon is a win­dow in­to a lost world, an ev­o­lu­tion­ary ex­pe­ri­ment where palms grew be­neath spruce trees and the in­sects in­clud­ed a mix­ture of Ca­na­di­an and Aus­tral­ian spe­cies. Discov­er­ing mam­mals al­lows us to paint a more com­plete pic­ture of this lost world,” said Green­wood.

“The early Eo­cene is a time in the ge­o­log­i­cal past that helps us un­der­stand how pre­s­ent-day Can­a­da came to have the tem­per­ate plants and an­i­mals it has to­day,” Green­wood said. “Howev­er, it can al­so help us un­der­stand how the world may change as the glob­al cli­mate con­tin­ues to war­m.”

Source : world-science.net

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