science

Ichthyosauromorpha

Ichthyosauromorpha is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ichthyosauromorpha rather than just read about it. In short: 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.

Key takeaways

Ichthyosauromorpha belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ichthyosauromorpha to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ichthyosauromorpha from memory before moving on to harder problems.

Reference excerpt

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) probably originated prior to the end of 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 even in their earliest known representatives, though they are usually considered to be diapsids. Ichthyosaur researcher Michael Maisch has alternatively argued that the group (or at least Ichthyosauriformes, as he regards hupehsuchians as unrelated) may have its origins within the primitive, non-diapsid lizard-like reptile group Procolonophoidea. 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.

Cladogram after Simões et al. 2022:

Taxonomy Clade Ichthyosauromorpha Order Hupehsuchia Clade Ichthyosauriformes Clade Nasorostra Superorder Ichthyopterygia

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

References

Illustrations

Worked examples

Example 1 — a first encounter with Ichthyosauromorpha

Start with the simplest possible case. Write down what Ichthyosauromorpha claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ichthyosauromorpha before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ichthyosauromorpha ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ichthyosauromorpha

In research: Ichthyosauromorpha appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ichthyosauromorpha in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ichthyosauromorpha is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fossil taxa described in 2014, Ichthyosauromorpha, Olenekian first appearances, so understanding it makes those chapters shorter.
In everyday life: Look for Ichthyosauromorpha outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Ichthyosauromorpha in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ichthyosauromorpha means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Ichthyosauromorpha out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ichthyosauromorpha in simple terms?

Why does Ichthyosauromorpha matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ichthyosauromorpha?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ichthyosauromorpha.