AboutZoos, Since 2008


Gigan­tic mam­malian car­ni­vore dis­cov­ered — fos­sils found in museum drawer in Kenya

pub­lished 21 April 2019 | mod­i­fied 21 April 2019

Pale­on­tol­o­gists at Ohio Uni­ver­sity have dis­cov­ered a new species of meat-​eating mam­mal larger than any big cat stalk­ing the world today. Larger than a polar bear, with a skull as large as that of a rhi­noc­eros and enor­mous pierc­ing canine teeth, this mas­sive car­ni­vore would have been an intim­i­dat­ing part of the east­ern African ecosys­tems occu­pied by early apes and monkeys.

Simbakubwa reconstructionSim­bakubwa kutokaafrika was a car­ni­vore that lived about 22 mil­lion years ago.
Illus­tra­tion (and recon­struc­tion) by Mauri­cio Anton

In a new study pub­lished online on 17 April in the Jour­nal of Ver­te­brate Pale­on­tol­ogy, the researchers name Sim­bakubwa kutokaafrika, a gigan­tic car­ni­vore known from most of its jaw, por­tions of its skull, and parts of its skele­ton. The 22-​million-​year-​old fos­sils were unearthed in Kenya decades ago as researchers can­vassed the region search­ing for evi­dence of ancient apes. Spec­i­mens were placed in a drawer at the National Muse­ums of Kenya and not given a great deal of atten­tion until Ohio Uni­ver­sity researchers Dr. Nancy Stevens and Dr. Matthew Borths redis­cov­ered them, rec­og­niz­ing their significance.

Open­ing a museum drawer, we saw a row of gigan­tic meat-​eating teeth, clearly belong­ing to a species new to science.

Dr. Matthew Borths, lead author, Depart­ment of Bio­med­ical Sci­ences, Her­itage Col­lege of Osteo­pathic Med­i­cine, Ohio Cen­ter for Ecol­ogy and Evo­lu­tion­ary stud­ies, Athens, USA

simbakubwa vs lionSim­bakubwa jaw vs lion skull.
Credit: Ohio Uni­ver­sity
is Swahili for ‘big lion’ because the ani­mal was likely at the top of the food chain in Africa, as lions are in mod­ern African ecosys­tems. Yet Sim­bakubwa was not closely related to big cats or any other mam­malian car­ni­vore alive today. Instead, the crea­ture belonged to an extinct group of mam­mals called hyaenodonts.

Hyaen­odonts were the first mam­malian car­ni­vores in Africa. For about 45 mil­lion years after the extinc­tion of the non-​avian dinosaurs, hyaen­odonts were the apex preda­tors in Africa. Then, after mil­lions of years of near-​isolation, tec­tonic move­ments of the Earth’s plates con­nected Africa with the north­ern con­ti­nents, allow­ing flo­ral and fau­nal exchange between land­masses. Around the time of Sim­bakubwa, the rel­a­tives of cats, hye­nas, and dogs began to arrive in Africa from Eurasia.

As the rel­a­tives of cats and dogs were going south, the rel­a­tives of Sim­bakubwa were going north. “It’s a fas­ci­nat­ing time in bio­log­i­cal his­tory,” Borths says. “Lin­eages that had never encoun­tered each other begin to appear together in the fos­sil record.”

simbakubwa and human silhouetteThe species name, kutokaafrika, is Swahili for ‘com­ing from Africa’ because Sim­bakubwa is the old­est of the gigan­tic hyaen­odonts, sug­gest­ing this lin­eage of giant car­ni­vores likely orig­i­nated on the African con­ti­nent and moved north­ward to flour­ish for mil­lions of years.

Ulti­mately, hyaen­odonts world­wide went extinct. Global ecosys­tems were chang­ing between 18 and 15 mil­lion years ago as grass­lands replaced forests and new mam­malian lin­eages diver­si­fied. “We don’t know exactly what drove hyaen­odonts to extinc­tion, but ecosys­tems were chang­ing quickly as the global cli­mate became drier. The gigan­tic rel­a­tives of Sim­bakubwa were among the last hyaen­odonts on the planet,” remarks Borths.

This is a piv­otal fos­sil, demon­strat­ing the sig­nif­i­cance of museum col­lec­tions for under­stand­ing evo­lu­tion­ary his­tory,” notes Stevens, Pro­fes­sor in the Her­itage Col­lege of Osteo­pathic Med­i­cine at Ohio Uni­ver­sity and co-​author of the study. “ Sim­bakubwa is a win­dow into a bygone era. As ecosys­tems shifted, a key preda­tor dis­ap­peared, herald­ing Ceno­zoic fau­nal tran­si­tions that even­tu­ally led to the evo­lu­tion of the mod­ern African fauna.”

This dis­cov­ery under­scores both the impor­tance of sup­port­ing inno­v­a­tive uses [sic] of fos­sil col­lec­tions, as well as the impor­tance of sup­port­ing the research and pro­fes­sional devel­op­ment of tal­ented young post­doc­toral sci­en­tists like Dr. Borths,” said Daniel Marenda, a pro­gramme direc­tor at the National Sci­ence Foun­da­tion, which funded this research. “This work has the poten­tial to help us under­stand how species adapt — or fail to adapt in this case — to a rapidly chang­ing global climate.”

(Source: Ohio Uni­ver­sity media release, 18.04.2019)

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