Squalicorax sp. 

 

Not much is known about this species. Although lots of fossilized teeth and some vertebral centra have been found this species is still a mystery. However, many people are trying to expand their knowledge about this species.

The Squalicorax species were some formidable sharks which lived throughout the entire Cretaceous period but then were extinct. Being a cartilaginous creature, they are primarily known from the fossilized vertebral centra of older individuals and for their teeth which are found all around the world. The teeth from Squalicorax look very much the same as the teeth of the modern tiger shark. In the beginning when these teeth were first found, they were described as being teeth from the species Galeocerdo (Benjamin F. Mudge in his report to the Board of Agriculture wrote that he found some pieces of the shark Galeocerdo falcatus) , this was mainly based upon the solidity of the teeth (today we know Galeocerdo teeth have a hollow cavity within). Also the form of the teeth looks very much like the teeth of Galeocerdo. With the serrations being the most obvious commonality, although these are very small there is one species (Squalicorax yangaensis) which has some rather large serrations. And of course the general shape of the tooth, being almost triangular in form with a nicely curved mesial cutting edge, an almost straight distal cutting edge followed by the heel (S. kaupi, S yangaensis, S. curvatus). If you compare this with the Galeocerdo teeth you can not deny the similarities in toth shape. It is also known that Tiger sharks are opportunistic feeders that actively scavenge. And looking at fossil evidence it may be concluded that Squalicorax was an opportunistic feeder as well. The fossilized remains of decayed Hadrosaurs and Tetrapods have been discovered with embedded teeth of the Squalicorax. But with the fact that Squalicorax was extinct at the end of the Cretaceous, and that there hasn’t been a find of a fossil linking these two species together this is the closest we will come in comparing these two different species. 

The name Squalicorax was given to the genus in 1939 by Whitley, before this period the genus was originally just known as “Corax”. (E.g. Corax falcatus Agassiz 1843). However there is a more common name for this genus, the “Crow shark”.  I’ve tried to discover (as did others with me) the origin of this name, but there are no publications of any kind which give an explanation for this name. So here’s my try. If you type in the word Corax at Google you get several links to the common raven (Corvus corax). This bird is known to be a scavenging bird. Also Corax is the Greek word for raven or crow. The origin however will remain a mystery until someone comes up with a paper showing the origin of this common name. 

 

The Squalicorax are placed in the family Anacoracidae, but there is some disagreement as to which order this family belongs. Capetta has done several researches and provided his reasons for placing it in the order Lamniformes. Shimada and Cicimurri found no definitive characteristics, so they concluded that Squalicorax was a Lamnoid with Carcharhinoid –like adaptions.

Below is a list of the different species of Squalicorax. Beside each specie is a reference to where the species can be found and a remark if there are any pictures of these species in the photographic library.

Order: Lamniformes.


       Family: Anacoracidae 


               Genus: Squalicorax 

-          Squalicorax africanus (Capetta 1991) found at: Egypt; Jordan; khouribga, Morocco; Syria (see pictures)

-          Squalicorax aulaticus ( Glickman & Itshenko, 1980) found at: Dzhyrakhuduk, Uzbekistan

-          Squalicorax australis ( Chapman, 1909) found at:Angola; Queensland, Australia

-          Squalicorax baharijensis (Stromer, 1927) found at : Egypt; France

-          Squalicorax bassanii (Gemmelaro, 1980) found at: Egypt; Israel; Ruseita, Jordan; houribga, Morocco (see pictures)

-          Squalicorax coquandi found at: France

-          Squalicorax curvatus (Williston, 1900) foundat:  Tykbutak, Kazakhstan; Gove county, Kansas,  Texas, U.S.A. (see pictures)

-          Squalicorax dolloi (Leriche, 1929) found at: Lonzeel, Belgium; Chilsay, Aktjubinsk, Kazakhstan

-          Squalicorax falcatus (Agassiz, 1843) found at: Tykbutak, Kazakhstan; Austin, Texas, Gove county, Kansas, U.S.A. (see pictures)

-          Squalicorax cf intermedius (Gluckman and Shvazhaite, 1971) found at; France

-          Squalicorax kaupi (Agassiz, 1845) found at: Africa; Europe; Japan; Kazakhstan; New Zeeland; U.S.A. (see pictures)

-          Squalicorax microserratodon (Shimada, 2008) found at: Western Kansas, U.S.A.

-          Squalicorax praeyangensis found at: Tykbutak, Mangyshlak, Kazakhstan

-          Squalicorax primaevus (Dalinkevicius, 1935) found at: West Australia; England; France

-          Squalicorax pristodontus (agassiz, 1843) found at: Belgium; Jordan; Madagascar; Mexico; Morocco; Netherlands; U.S.A. (see pictures)

-          Squalicorax santonicus (Gluckman & Zhelesko, 1979) found at: Kazakhstan; Russia

-          Squalicorax volgensis (Gluckman, 1979) found at: France

-          Squalicorax yangaensis (Darteville & Caiser, 1943) found at: Khouribga, Morocco; Syria (see pictures)

 

 

Below a schematic drawing of the morphological chance in the teeth of the different species

Danian (paleocene)

 

 

 

 

S. kaupi 


S.pristodontus 

Maastrichtian

U

 

 

M

 

 

L

 

 

Campanian

U

 

 

M

 

  

 

S. falcatus

L

 

Santonian

 

 

 

Coniacan

 

 

 

 

Turonian

 

 

 

 

Cenomanian

U

 

 

M

 

 

L

S. curvatus

 

 

Albian

 

U

 

 

 

 

M

L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                               Morphological change 

Modified from Shimada and Cicimurri, 2006, with Shimada's permission.

 

 

References:

 ** Druckenmiller, P.S., A.J. daun, J.L.Skulan and J.C. Pladziewicz, 1993. Stomach contents in the upper Cretaceous shark Squalicorax falcatus. Journal of vertebrate paleontology

** Schwimmer, D.R., J.D. Stewart, and G.D. Williams, 1997. scavenging by sharks of the genus Squalicorax in the late Cretaceous of North America

** Shimada, K. and Cicimurri, D.J. 2005. Skeletal anatomy of the late Cretaceous shark, Squalicorax.

** Shimada, K. 2008. New anacoracid shark fromupper Cretaceous Niobrara chalk of western Kansas, U.S.A.

** Shawn A. Hamm and Kenshu Shimada. The late Cretaceous anacoracid shark, Pseudocorax laevis (Leriche), from the Niobrara Chalk of western Kansas

** R. Vullo, H. Capetta and D. Neraudeau. New sharks and rays from the Cenomanian and Turonian of Charentes, France

** P.J.Smart, 2007. Anacoracid shark teeth (chondrichthyes, Vertebrata) from the early Cretaceous Albian sediments of Leighton Buzzard, south-central England