biology

Leidyosuchus

Leidyosuchus is a biology 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 Leidyosuchus rather than just read about it. In short: Leidyosuchus (meaning "Leidy's crocodile") is an extinct genus of eusuchian, either an alligatoroid crocodilian or a stem-group crocodilian, from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis.

Key takeaways

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

Reference excerpt

Leidyosuchus (meaning "Leidy's crocodile") is an extinct genus of eusuchian, either an alligatoroid crocodilian or a stem-group crocodilian, from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis. It is known from a number of specimens from the middle Campanian age Dinosaur Park Formation. It was a medium-sized alligatoroid, with a maximum skull length greater than 40 centimeters (16 in).

A number of species had been assigned to this genus over the years, including: L. acutidentatus (Sternberg, 1932), from the Paleocene of Saskatchewan; L. formidabilis (Erickson, 1976), from the Paleocene of North Dakota and Wyoming; L. gilmorei (Mook, 1942), from the Campanian of Alberta; L. multidentatus (Mook, 1930); L. riggsi (Schmidt, 1938); L. sternbergii (Gilmore, 1910), from the Maastrichtian (Late Cretaceous) of Colorado, Montana, North Dakota, South Dakota, and Wyoming; and L. wilsoni (Mook, 1959), from the Eocene of Wyoming. However, in 1997 Chris Brochu reevaluated the genus and reassigned most of the species, transferring L. acutidentatus, L. formidabilis, L. sternbergii, and L. wilsoni to the new genus Borealosuchus, and L. multidentatus to the new genus Listrognathosuchus, proposing L. gilmorei as a synonym of L. canadensis, and finding L. riggsi to be too fragmentary to be determinable.

Classification Leidyosuchus is one of the basal-most members of the superfamily Alligatoroidea. Leidyosuchus's placement within Alligatoroidea can be shown in the cladogram below, based on a 2018 tip dating study by Lee & Yates that simultaneously used morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data.

In a 2025 study, however, Jules D. Walter and colleagues argue that many character states previously thought to be diagnostic for alligatoroids were actually much more widespread. In their analysis several genera traditionally viewed as basal alligatoroids, among them Leidyosuchus, were found to not only fall outside of Alligatoroidea but to not even be true crocodilians, instead representing derived non-crocodilian eusuchians. Leidyosuchus was recovered as having split from the lineage leading up to Crocodilia before Deinosuchus and the terrestrial Planocraniidae.

References

Illustrations

Worked examples

Example 1 — a first encounter with Leidyosuchus

Start with the simplest possible case. Write down what Leidyosuchus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, 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 Leidyosuchus 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 Leidyosuchus 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 Leidyosuchus

In research: Leidyosuchus appears in biology 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 Leidyosuchus 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: Leidyosuchus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alligatoroidea, Fossil taxa described in 1907, Fossils of Canada, so understanding it makes those chapters shorter.
In everyday life: Look for Leidyosuchus 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 Leidyosuchus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Leidyosuchus 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 Leidyosuchus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Leidyosuchus in simple terms?

Why does Leidyosuchus matter?

Because it connects several biology 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 Leidyosuchus?

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 Leidyosuchus.