Sebecus (meaning "Sebek" in Latin) is an extinct genus of sebecid crocodylomorph from Eocene of South America.

Simpson described the type species, S. icaeorhinus, from a fragmented skull and lower jaw found in the Sarmiento Formation.

[4] Another American paleontologist, Edwin Harris Colbert, completed Simpson's work, thoroughly describing the genus and placing it in a new family, Sebecidae.

[5] The name Sebecus is a Latinisation of Sebek (also called Sobek), the crocodile god of ancient Egypt.

[4] In 1965, American paleontologist Wann Langston, Jr. named a second species, S. huilensis, from the Miocene Honda Group at the La Venta locality in Colombia.

[8] A third species of Sebecus, S. querejazus, was named in 1991 from the early Paleocene Santa Lucia Formation in Bolivia.

Langstonia huilensis, named after Langston, was distinguished from Sebecus by its narrower snout and widely spaced teeth.

Zulmasuchus querejazus, named after Zulma Gasparini, one of the authors of the study, differs from Sebecus in its wider snout.

Its limbs, especially femora, were proportionally longer than limbs of living crocodilians; the shoulder-to-hip length of its body can be estimated at 2.3 times the length of the femur - similar to another, unrelated terrestrial crocodylomorph, Boverisuchus, while American alligators have proportionally shorter femora.

Along with the broad downturned "wings" formed by the pterygoid and ectopterygoid bones at the bottom of the skull, this articulation restricts the jaw to up-and-down movement.

In contrast, living crocodilians have circular, widely spaced teeth and usually consume their food in large pieces.

[14] Ultrastructural analyses using electron microscopes have revealed microwear scratches on the teeth that are suggestive of this form of cutting.

The deep snout of Sebecus makes the shape of its brain somewhat different from those of living crocodiles, although its structure is the same.

Colbert interpreted the smaller cerebrum of Sebecus as a sign of primitiveness, with an evolutionary trend toward larger brain size in crocodilians.

[15] Larsson found that Sebecus and Allosaurus fragilis had similar ratios to C. saharicus, falling within the 95% confidence range characterizing living reptile species.

Living crocodilians have a straight retroarticular process at the back of the jaw and a low point of origin for the depressor muscle.

[4] Because it is represented by relatively complete fossil material, Sebecus has been used to define larger groups of crocodyliforms such as Sebecidae and Sebecosuchia.

The suborder Sebecosuchia was established to group Sebecus with Baurusuchus and has grown to include many other sebecid and baurusuchid members.

Turner and Calvo (2005) considered Sebecosuchia to be the sister taxon of Notosuchia and placed Sebecus as a basal member the clade.