Excalibosaurus

Name: Excalibosaurus ‭(‬Excalibur lizard‭)‬.
Phonetic: Ecks-kal-e-boe-sore-us.
Named By: McGowan‭ ‬-‭ ‬1986.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Ichthyosauria,‭ ‬Eurhinosauria,‭ ‬Leptopterygiidae.
Species: E.‭ ‬costini‭ (‬type‭)‬.
Diet: Piscivore.
Size: 7‭ ‬meters long,‭ ‬skull from the back to the tip of the snout is‭ ‬1.54‭ ‬meters long.
Known locations: England.
Time period: Sinemurian of the Jurassic.
Fossil representation: Two specimens,‭ ‬one of which is almost complete.

       The holotype specimen of Excalibosaurus was discovered in‭ ‬1984,‭ ‬and consisted of partial remains of a skull and some of the post cranial skeleton such as ribs,‭ ‬vertebrae,‭ ‬forefin and an incomplete pectoral girdle.‭ ‬When pieced together these remains recreated an individual that was estimated to have been up to four meters long,‭ ‬however this individual now seems to have been a juvenile.‭ ‬A second and almost complete specimen discovered in‭ ‬1996‭ ‬was of a larger seven meter long individual,‭ ‬a discovery which indicates that Excalibosaurus was probably at least a medium sized ichthyosaur.
       The features of Excalibosaurus that stands out the most are its asymmetrical jaws,‭ ‬with the rostrum of the upper jaw extending well beyond the end of the lower jaw.‭ ‬It’s possible that Excalibosaurus may have used this elongated rostrum to swipe at fish in a similar manner as a swordfish does.‭ ‬This would mean that Excalibosaurus did not need the precision to chase a fish to the point that it could catch it with its mouth,‭ ‬just get close‭ ‬enough to swipe it with its rostrum.‭ ‬This would cause injury to the fish,‭ ‬inhibiting its ability to swim away so that Excalibosaurus would have an easier time getting the fish into its mouth.‭ ‬Such behaviour might suggest a preference for smaller fish that were too agile for other and less specialised ichthyosaurs to catch.
       Two ichthyosaurs that are related to Excalibosaurus‭ ‬are Leptonectes from the late Triassic,‭ ‬and Eurhinosaurus that is also from the Early Jurassic.‭ ‬Additionally Excalibosaurus was once thought to be a synonym to Eurhinosaurus by some until the discovery of the second specimen in‭ ‬1996‭ ‬which revealed without question that Excalibosaurus is‭ ‬different enough to deserve classification as‭ ‬its own distinct genus.

Further reading
- A putative ancestor for the swordfish-like ichthyosaur Eurhinosaurus - C. McGowan - 1986.
- A new Specimen of Excalibosaurus from the English Lower Jurassic - C. McGowan - 2003.



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