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February 14, 2008

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Two strange dinos, one dark hunger

Feb. 14, 2008
Courtesy University of Chicago
and World Science staff

Eocarcharia (© Todd Marshall, courtesy Project Exploration)

Two 110 million-year-old di­no­saurs just un­earthed in the Sa­hara Des­ert high­light the un­usu­al meat-ea­ters that prowled south­ern con­ti­n­ents dur­ing the Cre­ta­ceous per­i­od, re­search­ers say. 

Named Kryp­tops and Eo­car­charia, the fos­sils were found in 2000 on an ex­pe­di­tion led by Uni­ver­s­ity of Chi­ca­go pa­le­on­tolo­g­ist Paul Sereno. They’re de­scribed in a pa­per this month in the sci­en­tif­ic jour­nal Ac­ta Pa­la­e­on­to­log­ica Po­lo­ni­ca.

Sereno and co-author pa­le­on­tolo­g­ist Ste­phen Bru­satte of the Uni­ver­s­ity of Bris­tol, U.K., say the fos­sils of­fer a glimpse of a rath­er early stage in the ev­o­lu­tion of the strange meat-ea­ters of Gond­wa­na, the south­ern “su­per­con­ti­nent” of the di­no­saur era. 

Dur­ing the Cre­ta­ceous, modern-day Af­ri­ca and South Amer­i­ca were be­gin­ning to sep­a­rate af­ter hav­ing been un­ited as part of Gond­wa­na.

Kryptops (© Todd Marshall, courtesy Project Exploration)

“T. rex has be­come such a fix­ture of Cre­ta­ceous lore, most peo­ple don’t real­ize that no ty­ran­no­saur ev­er set foot” be­low the equa­tor, said Sereno. In­stead, he added, dis­tinc­tive meat-ea­ters arose there, some with lit­tle in com­mon with the “tyrant king” be­yond a taste for fresh meat. 

Short-snouted Kryp­tops palaios, or “old hid­den face,” was named for a horny cov­er­ing that seems to have blan­keted most of its face, pa­le­on­tologists said. It probably ate like “a fast, two-legged hy­e­na gnaw­ing and pulling apart a car­cass,” Bru­satte said. 

Kryptops (above), Eocarcharia (below). (© Todd Marshall, courtesy Project Exploration)

Like la­ter mem­bers of its line­age, called abe­li­saur­ids, in South Amer­i­ca and In­dia, Kryp­tops had short, ar­mored jaws with small teeth that would have been bet­ter at gob­bling guts and gnaw­ing car­casses than snap­ping at live prey, the re­search­ers said. 

The vo­ra­cious rep­tile was mea­sured at 25 feet (8 me­ters) long.

A similar-sized con­tem­po­rary, Eo­car­charia dinops or “fierce-eyed dawn shark,” is so named for its blade-shaped teeth and prom­i­nent bony eye­brow. Un­like Kryp­tops, its teeth were de­signed for dis­abling live prey and sev­ering body parts, ac­cord­ing to Sereno and col­leagues. 

Eo­car­charia and kin, called car­char­o­don­to­sau­r­ids, pro­duced the south­ern con­ti­nents’ larg­est preda­tors, match­ing or ex­ceed­ing T. rex in size, they added. 

Eo­car­charia’s brow was swol­len in­to a mas­sive band of bone, giv­ing it a men­ac­ing glare. Se­re­noand Bru­satte sug­gest in the pa­per that the ro­bust bony brow in Eo­car­charia and kin may have been used as a bat­ter­ing ram against ri­vals in fights over mates. “Brow-beating may not be far from the truth,” ven­tured Se­re­no. 

The fos­sil ar­ea, in pre­s­ent-day Ni­ger, was home to a panoply of bi­zarre spe­cies, the re­search­ers said. 

Hyena-like Kryp­tops; shark-toothed Eo­car­cha­ria; and fish-eating, sail-backed Su­cho­mi­mus (“cro­co­dile mim­ic”) are a car­ni­vore tri­o that char­ac­ter­izes the Cre­ta­ceous per­i­od in Af­ri­ca and pos­sibly oth­er south­ern land­masses, they added. These beasts preyed on the ground-grubbing, long-necked plant-ea­ter Ni­ger­sau­rus and lived along­side an enor­mous ex­tinct croc­o­dil­ian nick­named “Su­per­Croc” (Sar­co­su­chus).

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Two 110 million-year-old dinosaurs just unearthed in the Sahara Desert highlight the unusual meat-eaters that prowled southern lands during the Cretaceous Period, researchers say. Named Kryptops and Eocarcharia, the fossils were found in 2000 on an expedition led by University of Chicago paleontologist Paul Sereno. They’re described in a paper this month in the scientific journal Acta Palaeontologica Polonica. Sereno and co-author paleontologist Stephen Brusatte of the University of Bristol, U.K., say the fossils offer a glimpse of a rather early stage in the evolution of the strange meat-eaters of Gondwana, a southern “supercontinent” of the dinosaur era. During the Cretaceous, modern-day Africa and South America were beginning to separate after having been united as part of Gondwana. “T-rex has become such a fixture of Cretaceous lore, most people don’t realize that no tyrannosaur ever set foot” below the equator, said Sereno. Instead, he added, distinctive meat-eaters arose there, some with little in common with the “tyrant king” beyond a taste for fresh meat. Short-snouted Kryptops palaios, or “old hidden face,” was named for a horny covering that seems to have blanketed most of its face, paleontologists said. It probably ate like “a fast, two-legged hyena gnawing and pulling apart a carcass,” Brusatte said. Like later members of its lineage, called abelisaurids, in South America and India, Kryptops had short, armored jaws with small teeth that would have been better at gobbling guts and gnawing carcasses than snapping at live prey, the researchers said. About 25 feet (8 meters) long, Kryptops was a voracious meat-eater. A similar-sized contemporary, Eocarcharia dinops, or “fierce-eyed dawn shark,” is so named for its blade-shaped teeth and prominent bony eyebrow. Unlike Kryptops, its teeth were designed for disabling live prey and severing body parts, according to Sereno and colleagues. Eocarcharia and kin, called carcharodontosaurids, produced the southern continents’ largest predators, matching or exceeding T. rex in size, they added. Eocarcharia’s brow was swollen into a massive band of bone, giving it a menacing glare—”brow-beating may not be far from the truth,” remarked Sereno. He and Brusatte suggest in the paper that the robust bony brow in Eocarcharia and kin may have been used as a battering ram against rivals in fights over mating. The fossil area, in present-day Niger, was home to a panoply of bizarre species, the researchers said. Hyena-like Kryptops; shark-toothed Eocarcharia; and fish-eating, sail-backed Suchomimus (“crocodile mimic”) are a carnivore trio that characterizes the Cretaceous Period in Africa and possibly other southern landmasses, they added. These beasts preyed on the ground-grubbing, long-necked plant-eater Nigersaurus and lived alongside an enormous extinct crocodilian nicknamed “SuperCroc” (Sarcosuchus).