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Paleontologists trace origin of millipedes, crabs and insects to new 508 million-year-old sea creature with “can opener”- like pincers

April 26, 2017

Toron­to, ON – Pale­on­tol­o­gists at the Uni­ver­si­ty of Toron­to (U of T) and the Roy­al Ontario Muse­um (ROM) have uncov­ered a new fos­sil species that sheds light on the ori­gin of mandibu­lates, the most abun­dant and diverse group of organ­isms on Earth, to which belong famil­iar ani­mals such as flies, ants, cray­fish and cen­tipedes. The find­ing was announced in a study pub­lished today in Nature.

The crea­ture, named Tokum­mia katalep­sis by the researchers, is a new and excep­tion­al­ly well-pre­served fos­silized arthro­pod – a ubiq­ui­tous group of inver­te­brate ani­mals with seg­ment­ed limbs and hard­ened exoskele­tons. Tokum­mia doc­u­ments for the first time in detail the anato­my of ear­ly “mandibu­lates”, a hyper­di­verse sub-group of arthro­pods which pos­sess a pair of spe­cial­ized appendages known as mandibles, used to grasp, crush and cut their food. Mandibu­lates include mil­lions of species and rep­re­sent one of the great­est evo­lu­tion­ary and eco­log­i­cal suc­cess sto­ries of life on Earth.

“In spite of their colos­sal diver­si­ty today, the ori­gin of mandibu­lates had large­ly remained a mys­tery,” said Cédric Aria, lead author of the study and recent grad­u­ate of the PhD pro­gram in the Depart­ment of Ecol­o­gy & Evo­lu­tion­ary Biol­o­gy at U of T, now work­ing as a post-doc­tor­al researcher at the Nan­jing Insti­tute for Geol­o­gy and Palaeon­tol­ogy, in Chi­na. “Before now we’ve had only sparse hints at what the first arthro­pods with mandibles could have looked like, and no idea of what could have been the oth­er key char­ac­ter­is­tics that trig­gered the unri­valled diver­si­fi­ca­tion of that group.”

Tokum­mia lived in a trop­i­cal sea teem­ing with life and was among the largest Cam­bri­an preda­tors, exceed­ing 10 cm in length ful­ly extend­ed. An occa­sion­al swim­mer, the researchers con­clude its robust ante­ri­or legs made it a pre­ferred bot­tom-dweller, as lob­sters or man­tis shrimps today. Spec­i­mens come from 508 mil­lion-year-old sed­i­men­ta­ry rocks near Mar­ble Canyon in Koote­nay nation­al park, British Colum­bia. Most spec­i­mens at the basis of this study were col­lect­ed dur­ing exten­sive ROM-led field­work activ­i­ties in 2014.

“This spec­tac­u­lar new preda­tor, one of the largest and best pre­served soft-bod­ied arthro­pods from Mar­ble Canyon, joins the ranks of many unusu­al marine crea­tures that lived dur­ing the Cam­bri­an Explo­sion, a peri­od of rapid evo­lu­tion­ary change start­ing about half a bil­lion years ago when most major ani­mal groups first emerged in the fos­sil record,” said co-author Jean-Bernard Caron, senior cura­tor of inver­te­brate pale­on­tol­ogy at the ROM and an asso­ciate pro­fes­sor in the Depart­ments of Ecol­o­gy & Evo­lu­tion­ary Biol­o­gy and Earth Sci­ences at U of T.

Analy­sis of sev­er­al fos­sil spec­i­mens, fol­low­ing care­ful mechan­i­cal prepa­ra­tion and pho­to­graph­ic work at the ROM, showed that Tokum­mia sport­ed broad ser­rat­ed mandibles as well as large but spe­cial­ized ante­ri­or claws, called max­il­lipeds, which are typ­i­cal fea­tures of mod­ern mandibu­lates.

“The pin­cers of Tokum­mia are large, yet also del­i­cate and com­plex, remind­ing us of the shape of a can open­er, with their cou­ple of ter­mi­nal teeth on one claw, and the oth­er claw being curved towards them,” said Aria. “But we think they might have been too frag­ile to be han­dling shelly ani­mals, and might have been bet­ter adapt­ed to the cap­ture of siz­able soft prey items, per­haps hid­ing away in mud. Once torn apart by the spiny limb bases under the trunk, the mandibles would have served as a rev­o­lu­tion­ary tool to cut the flesh into small, eas­i­ly digestible pieces.”

The body of Tokum­mia is made of more than 50 small seg­ments cov­ered by a broad two-piece shell-like struc­ture called a bivalved cara­pace. Impor­tant­ly, the ani­mal bears sub­di­vid­ed limb bases with tiny pro­jec­tions called endites, which can be found in the lar­vae of cer­tain crus­taceans and are now thought to have been crit­i­cal inno­va­tions for the evo­lu­tion of the var­i­ous legs of mandibu­lates, and even for the mandibles them­selves.

The many-seg­ment­ed body is oth­er­wise rem­i­nis­cent of myr­i­apods, a group that includes cen­tipedes, mil­li­pedes, and their rel­a­tives. “Tokum­mia also lacks the typ­i­cal sec­ond anten­na found in crus­taceans, which illus­trates a very sur­pris­ing con­ver­gence with such ter­res­tri­al mandibu­lates,” said Aria.

The study also resolves the affini­ties of oth­er emblem­at­ic fos­sils from Canada’s Burgess Shale more than a hun­dred years after their dis­cov­ery. “Our study sug­gests that a num­ber of oth­er Burgess Shale fos­sils such as Bran­chio­caris, Canadaspis and Odara­ia form with Tokum­mia a group of crus­tacean-like arthro­pods that we can now place at the base of all mandibu­lates,” said Aria.

The ani­mal was named after Tokumm Creek, which flows through Mar­ble Canyon in north­ern Koote­nay Nation­al Park, and the Greek for “seiz­ing”. The Mar­ble Canyon fos­sil deposit was first dis­cov­ered in 2012 dur­ing prospec­tion work led by the Roy­al Ontario Muse­um and is part of the Burgess Shale fos­sil deposit, which extends to the north into Yoho Nation­al Park in the Cana­di­an Rock­ies. All spec­i­mens are held in the col­lec­tions of the Roy­al Ontario Muse­um on behalf of Parks Cana­da.

The Burgess Shale fos­sil sites are locat­ed with­in Yoho and Koote­nay nation­al parks in British Colum­bia. The Burgess Shale was des­ig­nat­ed a UNESCO World Her­itage Site in 1980. Parks Cana­da is proud to pro­tect these glob­al­ly sig­nif­i­cant palaeon­to­log­i­cal sites, and to work with lead­ing sci­en­tif­ic researchers to expand knowl­edge and under­stand­ing of this key peri­od of earth his­to­ry. New infor­ma­tion from ongo­ing sci­en­tif­ic research is con­tin­u­al­ly incor­po­rat­ed into Parks Canada’s Burgess Shale edu­ca­tion and inter­pre­ta­tion pro­grams, which include guid­ed hikes to these out­stand­ing fos­sil sites.

The find­ings are described in the paper “‘Burgess Shale fos­sils illus­trate the ori­gin of the mandibu­late body plan”. Fund­ing for the research was pro­vid­ed pri­mar­i­ly by a Nat­ur­al Sci­ences and Engi­neer­ing Research Coun­cil of Cana­da Dis­cov­ery Grant (#341944) to Caron, and Roy­al Ontario Muse­um field­work grants.

– 30 –

Notes to media:

1) The paper will appear online at after the embar­go lifts.


Cédric Aria (bilin­gual – Eng­lish-French)
Post-doc­tor­al researcher
Nan­jing Insti­tute of Geol­o­gy and Palaeon­tol­ogy
+86 153 7100 2536 (mobile) (GMT +8)
Skype ID: c.aria

Alter­nate con­tact: Fangchen Zhao
 +86 137 7053 0436 (mobile), +86 25 8328 2176 (desk) (GMT +8)

Jean-Bernard Caron (bilin­gual – Eng­lish-French)
Senior Cura­tor of Inver­te­brate Palaeon­tol­ogy, Roy­al Ontario Muse­um and
Asso­ciate Pro­fes­sor, Depart­ments of Earth Sci­ences and Ecol­o­gy & Evo­lu­tion­ary Biol­o­gy
Uni­ver­si­ty of Toron­to (pre­ferred mode of com­mu­ni­ca­tion)
416 586 5593 (desk)

Sean Bet­tam­Com­mu­ni­ca­tions, Fac­ul­ty of Arts & Sci­ence
Uni­ver­si­ty of Toron­to
416 946 7950 (desk)

David McK­ay
Com­mu­ni­ca­tions Coor­di­na­tor
Roy­al Ontario Muse­um
416 586 5559 (desk)

Tania Peters
Pub­lic Rela­tions and Com­mu­ni­ca­tions Offi­cer
Parks Cana­da
+1 250 343 2005