User:Abyssal/Portal:Ichthyosauromorpha

The Ichthyosauromorpha Portal

Introduction

Hupehsuchus nanchangensis

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

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.

The Ichthyosauromorpha were previously thought to have likely originated in China during the upper Lower Triassic period, about 248 million years ago. However, a 2023 study recorded the fossils of a derived marine ichthyosauromorph (an ichthyopterygian) in earliest Triassic rocks of Spitsbergen, Norway, just 2 million years after the Permian–Triassic extinction event. The presence of such a derived ichthyosauromorph so early in the Triassic indicates that the ichthyosauromorphs (and possibly ichthyosauriformes, depending on divergence estimates) originated during the Permian and were thus survivors of the mass extinction as opposed to ecological successors that evolved following it.

One branch consists 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.

Their relationships with other reptiles are unresolved, due to their highly derived morphology and presumed ancient origins, even in their earliest known representatives, though they are usually considered to be diapsids. A 2022 study on the early evolution of reptiles classified the Ichthyosauromorpha as basal archosauromorphs, forming a clade with the other marine reptile groups Thalattosauria and Sauropterygia as sister to the rest of the Archosauromorpha. A 2023 study describing the Triassic marine reptile Prosaurosphargis found a similar placement, albeit instead placing the three marine reptile groups within an expanded Archelosauria. (Full article...)

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The Crystal Palace Dinosaurs, also known as Dinosaur Court, are a series of sculptures of extinct animals (including dinosaurs) and mammals in Crystal Palace Park, now in the London borough of Bromley. Commissioned in 1852 to accompany the Crystal Palace after its move from the Great Exhibition in Hyde Park and unveiled in 1854, they were the first dinosaur sculptures in the world, pre-dating the publication of Charles Darwin's On the Origin of Species by six years. While to varying degrees inaccurate by modern standards, the models were designed and sculpted by Benjamin Waterhouse Hawkins under the scientific direction of Sir Richard Owen, representing the latest scientific knowledge at the time. The models were classed as Grade II listed buildings from 1973, extensively restored in 2002, and upgraded to Grade I listed in 2007.

The models represent fifteen genera of extinct animals, not all dinosaurs. They are from a wide range of geological ages, and in addition to the dinosaurs include ichthyosaurs and plesiosaurs from the Mesozoic era, as well as some mammals from the more recent Cenozoic era. (see more...)

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Subcategories

Ichthyosauromorphs

Ichthyosauromorph genera

Hupehsuchians

Ichthyosauriforms

Triassic ichthyosauromorphs

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A skeleton of Barracudasauroides panxianensis collected from the ~247.2 million - ~242 million year old Anisian Guanling Formation of Guizhou Province‭, China. The specimen is 118 x 62 x 545 cm in size and 79.4 kg in mass.
Photo credit: Didier Descouens

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Did you know?

... that highlights from the history of ichthyosaur research include fossils of pregnant females (diagram pictured), whale-sized ichthyosaurs from Nevada, and ichthyosaurs with swordfish-like jaws?
...that the prehistoric marine reptile Excalibosaurus (pictured) was named after King Arthur's sword because of the sword-like appearance of its upper jaw?
... that an unnamed member of the extinct order Hupehsuchia exhibited an unusual form of polydactyly that is similar to that of some early tetrapods of the Devonian period?
... that the existence of a sea monster in Scotland has finally been proven?