Phantomosaurus

Phantomosaurus is an extinct genus of ichthyosaur, which existed during the late Anisian stage of the Middle Triassic. It would have been around 6 metres long, with a skull of 50 cm. Fossils of the species Phantomosaurus neubigi have been found in southern Germany. It was discovered and named in 1997 by Sander in the rocks of the Upper Muschelkalk. More recently, in 2005, the braincase was studied by Maisch and Matzke. They found it to be unique among all known ichthyosaurs in terms of braincase morphology. Despite its close relation to many other ichthyosaurs, in particular Cymbospondylus, Phantomosaurus appears to have a very primitive braincase which resembles other diapsids more than other ichthyosaurs. Phantomosaurus is known from a partial skull, the lower jaw, some of the vertebrae and ribs (pictured) and the hind fin. The hind fin is very long and slender, with elongated femur, tibia and fibula. These features suggest a long but not particularly powerful limb, which would have generated a reasonable quantity of lift. Presumably the fore fins also generated lift, or the ichthyosaur would have found itself permanently heading downwards. The anterior centrum of each vertebra has two symmetrical hollows in, possibly to aid buoyancy. The vertebrae also have ventro-lateral keels, for reasons unknown. Each zygapophysis is very long and extends a long way posteriorly - their articulatory facets are almost totally horizontal. The lower jaw is around 40 cm long and has many conical teeth for spearing fish. On the lateral surface, the articular is anterior to the suprangular. The skull is mostly disarticulated. Bones we have found are: left quadratojugal, postfrontal, supratemporal, postorbital, basioccipital and both tubera basioccipitalia, the parabasisphenoid, the otic capsule containing both opisthotic and prootic bones, exoccipital, supraoccipital and pterygoid.