Ichthyosauromorpha

The Ichthyosauromorpha are an extinct clade of marine reptiles consisting of the Ichthyosauriformes and the Hupehsuchia, living during the Mesozoic.

Ichthyosauromorpha
Temporal range:
Early Triassic - Late Cretaceous, 251.3–90 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Neodiapsida
Clade: †Ichthyosauromorpha
Motani et al., 2014
Subgroups

The node clade Ichthyosauromorpha was first defined by Ryosuke Motani et. al. in 2014 as the group consisting of the last common ancestor of Ichthyosaurus communis and Hupehsuchus nanchangensis, and all its descendants. Their synapomorphies, unique derived traits, include: the presence of an anterior flange on the humerus and radius; the lower end of the ulna being as wide as or wider than the upper end, the forelimb being as long as or longer than the hindlimb, the hand having at least three quarters of the length of the upper arm and lower arm combined, the fibula extending behind the level of the thighbone, and the transverse process of the vertebral neural arch being reduced or absent.[1]

The Ichthyosauromorpha probably originated in China during the upper Lower Triassic period, about 248 million years ago. One branch consisted of the Hupehsuchia, and the other of the Ichthyosauriformes, of which Cartorhynchus was a basal member. Other ichthyosauriforms were the Ichthyopterygia, containing the Ichthyosauria and allies. The last ichthyosaurs probably became extinct in the middle Cretaceous.

Taxonomy

Phylogeny

The internal phylogenetic structure of the Ichthyosauromorpha is shown by this cladogram:

Ichthyosauromorpha 
 

Hupehsuchia

 
 Ichthyosauriformes 
 

Nasorostra

 
 

Ichthyopterygia

 
 
 
gollark: That's how you would do it in my thing, using a somewhat insane S-expression assembly-ish language.
gollark: Using hypothetical assembly syntax I haven't actually implemented:```# start of memory to add kittens to(add r1 r0 0x1000) # maybe there would be nice dedicated syntax for "set register" actually# end of kittenized region(add r2 r0 0x1600)(label loop (add r3 r0 40) (poke r3 r1 0) (add r3 r0 94) (poke r3 r1 1) # and so on (add r1 r1 8) (jlt r1 r2 loop))```
gollark: To create RAM kittens, all you need to do is `ADD` the ASCII value of each character into a temporary register, `POKE` them into the right memory location (using the per-instruction `POKE` offset, probably), and then do that in a loop.
gollark: I should probably implement arithmetic instructions then a basic assembler, I guess, because hand-writing machine code is unpleasant.
gollark: What? No. This doesn't really need jumps, except possibly to run it repeatedly.

References
  1. Motani; et al. (2014). "A basal ichthyosauriform with a short snout from the Lower Triassic of China". Nature. 517 (7535): 485–488. doi:10.1038/nature13866. PMID 25383536.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.