Brancasaurus
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Brancasaurus Temporal range: Berriasian |
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| Holotype specimen | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: | † |
| Genus: |
†Brancasaurus Wegner, 1914 |
| Species: | †B. brancai |
| Binomial name | |
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Brancasaurus brancai Wegner, 1914 |
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| Synonyms | |
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Brancasaurus (meaning "Branca's lizard") is a genus of plesiosaur which lived in a freshwater lake in the Early Cretaceous of what is now North Rhine-Westphalia, Germany. With a long neck possessing vertebrae bearing distinctively-shaped "shark fin"-shaped neural spines, and a relatively small and pointed head, Brancasaurus is superficially similar to Elasmosaurus, albeit smaller in size at 3.26 metres (10.7 ft) in length.
The type species of this genus is Brancasaurus brancai, first named by Theodor Wegner in 1914 in honor of German paleontologist Wilhelm von Branca. Another plesiosaur named from the same region, Gronausaurus wegneri, most likely represents a synonym of this genus. While traditionally considered as a basal member of the Elasmosauridae, Brancasaurus has more recently been recovered as a member, or close relative, of the , a group containing many other freshwater plesiosaurs.
Brancasaurus was a medium-sized plesiosaur, at 3.26 metres (10.7 ft) in length; the holotype specimen is likely a subadult, judging by the unfused sutures in the vertebrae as well as the development of processes on the limbs and pubis.
The skull of the holotype, which measures 23.7 centimetres (9.3 in) long, is long and narrow, with a tapered snout that slopes downwards at an angle of 15°. The eye sockets were roughly the same size as the temporal openings immediately behind them. A narrow, rounded ridge along the middle of the top surface of the skull extends from near the front of the premaxilla to the back of the eye sockets. The frontal bones form a rectangular bar that separates the eye sockets down the middle. A ridge running across the bar intersects with the forward-extending ridge to produce a dagger-shaped protrusion. The jugal bone, which extends from the bottom of the eye socket back to the level of the temporal openings, is entirely bordered on its bottom by the maxilla. The squamosal bones arch around to form the curved back of the skull, and bear a ridge on top for attachment of neck muscles. There is also a ridge at the point where the two bones fuse. A cast of the braincase shows impressions of the semicircular canals and membranous inner ear, as well as canals of the hypoglossal, accessory, glossopharyngeal, and vagus nerves, which can also be observed on the bony exoccipital-opisthotic of the braincase. On the imperfectly-preserved lower jaw, the coronoid eminence seems to be relatively low, judging by the narrow and slightly curved top edge of the surangular bone. While the teeth have been lost, they were initially described as long, slender, and awl-shaped, with rough ridges on the outer surfaces. Although it has been suggested that Brancasaurus had very reduced tooth sockets in the premaxilla, as in , this is impossible to verify because of damage to this portion of the skull.
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Wikipedia