| Malawania | |
|---|---|
 | |
| Restoration | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | †Ichthyosauria |
| Family: | †Ichthyosauridae |
| Genus: | †Malawania Fischeret al.,2013 |
| Type species | |
| †Malawania anachronus Fischeret al., 2013 | |
Malawania is anextinctgenus ofbasalthunnosaurichthyosaur known from the middleEarly Cretaceous (Hauterivian orBarremian stage) ofIraq. Thetype species isMalawania anachronus and it was named by Valentin Fischer, Robert M. Appleby,Darren Naish, Jeff Liston, Riding, J. B., Brindley, S. andPascal Godefroit in2013 based on specimen NHMUK PV R6682.[1] It is unusual as it is much more primitive than other Cretaceous ichthyosaurs, being most closely related toIchthyosaurus from the Late Triassic and Early Jurassic, over 70 million years earlier thanMalawania, with all other known ichthyosaurs from theLate Jurassic onwards belonging to the familyOphthalmosauridae.
The holotype and only known specimen was discovered in 1952 by British petroleum geologistsD. M. Morton, F. R. S. Henson, R. J. Wetzel and L. C. F. Damesin while working in Chia Gara, Amadia inIraqi Kurdistan. The slab was being used to dam a small river and was part of a mule track. It was then transported back to the UK and donated to theNatural History Museum in 1959. Robert M. Appleby would study the specimen for many years until his death in 2004, but never published a paper, one manuscript submitted toPaleontology in 1979 was rejected due to the uncertain provenance of the specimen.[2] The specimen was formally described in 2013 by Fischer and colleagues. Usingpalynology it was determined that the rocks surrounding the specimen were Hauterivian-Barremian in age, which was unexpected given the archaic nature of the specimen.[1]
Eachlacrimal (paired bones at the front edges of theorbits) bears a hollow towards its front edge. Fischer and colleagues speculated that these may have been the location of thelacrimal glands (which produce thetear film). The long, backwards projecting processes of the lacrimals extend halfway underneath the orbits (eye sockets). The eyeballs were supported by rings of 13 bones, known assclerotic rings.[1]
Malawania has a minimum of fiveneck vertebrae. While the boundary between them is still demarcated, the first two vertebrae are fused. All of the knowncentra (vertebral bodies) are the same length, save for thefirst, which has a length double that of the rest. In some of thetrunk vertebrae, the forwards-placed facets for theribs flow smoothly together with the edges of the vertebrae. The well-spacedneural spines towards the front of the animal have trapezoidal tops, a unique feature of this genus. The cross sections of the ribs are bilobed.[1]
Unlikebaracromians, thescapulae (shoulder blades) ofMalawania have unemarginated front surfaces. The trapezoid-shapedhumeri (upper arm bones) are unusually short, a morphology unique to this genus. The upper end of each humerus bears a backwards-pointing projection known as a capitular process. This trait is also unique toMalawania, with the processes of other ichthyosaurs being semicircular. The humeri do not narrow at their middle, an atypical trait outside ofOphthalmosauridae. The lower ends of the humeri do not broaden significantly, each articulating with two bones, theradius andulna. These two six-sided bones are elongate and contact each other across the entirety of their inner margins, without an opening between them.[1]
With the exception of the quadrangularradiales (carpals below the radii), most of the hand bones ofMalawania are hexagon-shaped and tightly interlocked, similar toMacgowania. Theintermedia (a pair of wrist bones) approach the size of the radii, distinctive ofMalawania. Two digits originate from each intermedium, similar toIchthyosaurus. There are two other digits in the foreflippers ofMalawania for a total of four. The first digit would have had more than ninephalanges (digit bones) when complete, the first of these bearing a notch.[1]
The name is derived from "Kurdish ‘Malawan’: swimmer andLatinized Greek noun in apposition ‘anachronus’ meaning ‘out of time’."[1]
Malawania was found to be thesister taxon toIchthyosaurus.[1] Below is acladogram modified from Fischeret al., 2013.[1]
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