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Fossils of tiny, unknown hedgehog found

July 8, 2014
Courtesy of University of Colorado at Boulder
and World Science staff

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.

Courtesy of U. Colorado Boulder


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.”


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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 contemporary 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.”