Kryptops

Kryptops (meaning "covered face") is an extinct genus of possibly chimeric abelisaurid theropod dinosaurs from the Early Cretaceous of Niger. It is known from a partial maxilla (upper jaw bone) found at the Gadoufaoua locality in the western Ténéré Desert, in rocks of the Aptian–Albian-age Elrhaz Formation. The fossils were collected in 2000 by a University of Chicago expedition to Niger led by American paleontologist Paul Sereno. They were then described in 2008 by Sereno and Steve Brusatte. The genus contains a single species, Kryptops palaios. Sereno and Brusatte referred several postcranial remains to Kryptops, but later studies have shown that these elements belong to an allosauroid theropod, leaving Kryptops to be only known from the incomplete maxilla. Kryptops is one of the oldest known members of the Abelisauridae, making it vital to understanding this family's evolution. Its length is estimated to be around , making it smaller than later genera such as Carnotaurus. Nevertheless, Kryptops is a large, carnivorous dinosaur with highly serrated teeth (bearing many denticles) and robust upper jaws. The outer surface of its maxilla features deep striations, grooves, and rugosities, indicating it was covered in a tightly adhering integumentary structure like keratin.

Kryptops (meaning "covered face") is an extinct genus of possibly chimeric abelisaurid theropod dinosaurs from the Early Cretaceous of Niger. It is known from a partial maxilla (upper jaw bone) found at the Gadoufaoua locality in the western Ténéré Desert, in rocks of the Aptian–Albian-age Elrhaz Formation. The fossils were collected in 2000 by a University of Chicago expedition to Niger led by American paleontologist Paul Sereno. They were then described in 2008 by Sereno and Steve Brusatte. The genus contains a single species, Kryptops palaios. Sereno and Brusatte referred several postcranial remains to Kryptops, but later studies have shown that these elements belong to an allosauroid theropod, leaving Kryptops to be only known from the incomplete maxilla. Kryptops is one of the oldest known members of the Abelisauridae, making it vital to understanding this family's evolution. Its length is estimated to be around , making it smaller than later genera such as Carnotaurus. Nevertheless, Kryptops is a large, carnivorous dinosaur with highly serrated teeth (bearing many denticles) and robust upper jaws. The outer surface of its maxilla features deep striations, grooves, and rugosities, indicating it was covered in a tightly adhering integumentary structure like keratin. ==Discovery and naming== diagram including all the material initially included in the Kryptops holotype]] In 2000, an expedition conducted by the University of Chicago led by American paleontologist Paul Sereno and funded by the National Geographic Society explored fossiliferous sandstone outcrops in a site known as Gadoufaoua on the western edge of the Ténéré Desert of Niger. These layers belong to the Elrhaz Formation, which dates to the Aptian and Albian ages of the Early Cretaceous, around 112 million years ago. During the expedition, a maxilla (main tooth-bearing bone of the upper jaw) of a theropod was collected away from a set of elements consisting of three dorsal (back) vertebrae, two ribs, the , and the . These remains were then transported to the University of Chicago for study and preparation before being returned to the Musee National du Niger and deposited under the catalog number MNN GAD1. The maxilla was cataloged as MNN GAD1-1, whereas the postcranial fossils were assigned MNN GAD1-2 through MNN GAD1-8. These theropod remains were believed to belong to the same individual by Paul Sereno, who, with Jeffrey Wilson and Jack Conrad, later mentioned them in a 2004 paper as an undescribed abelisaurid. Sereno and Steve Brusatte described the fossils as the holotype (name-bearing) specimen of a new genus and species of abelisaurid in 2008, named Kryptops palaios. The generic name derives from the Ancient Greek words krypto, meaning , and ops, meaning , referencing the unique anatomy of the maxilla. The specific name, , is a Greek term meaning "old", in reference to the age of the fossils compared to related taxa.

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