science

Megachasma alisonae

Megachasma alisonae 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 Megachasma alisonae rather than just read about it. In short: Megachasma alisonae is an extinct species of megamouth shark that lived during the Eocene (Priabonian, ca. 36 mya). It is the oldest fossil record of a megamouth shark.

Key takeaways

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

Reference excerpt

Megachasma alisonae is an extinct species of megamouth shark that lived during the Eocene (Priabonian, ca. 36 mya). It is the oldest fossil record of a megamouth shark. The type fossil was recovered from the Søvind Marl Formation in Denmark and consists of a single tooth. Based on comparison with the teeth of the recent megamouth species (Megachasma pelagios), the length of the animal has been estimated at 1.3–3.5 m (4.3–11.5 ft).

Discovery and naming

The holotype and only known specimen of M. alisonae is NHMUK PV P73711, an isolated tooth. It is nearly complete and either belonged to the right side of the upper jaw or the left side of the lower jaw. It was discovered on a sea cliff in the Pyt Member of the Søvind Marl Formation in Denmark. The tooth was discovered in a bulk sediment sample from the upper 50 cm (20 in) of the member that was collected in 1988. The species was described by Kenshu Shimada and David J. Ward in 2016. The specific name honors Alison Ward, who aided David J. Ward with the work that resulted in the type specimen's discovery.

Classification M. alisonae belongs to the same genus as the modern megamouth shark and the extinct species Megachasma applegatei. Megachasma itself belongs to the family Megachasmidae. Molecular studies have estimated that this family arose in the Upper Cretaceous. Due to a lack of fossil material, it has been hypothesized that the dental changes in this family occurred slowly enough to make their teeth harder to differentiate from other families of sharks early in their evolution. The tooth morphology of M. alisonae has a greater resemblance to that of Odontaspididae than seen in the other species of Megachasma. This supports the hypothesis that Megachasmidae is closely related to a group of sharks with odontaspidid-like teeth, perhaps the odontaspids themselves. The tooth morphology of M. alisonae also provides information needed to identify older megachasmid fossils.

References

Worked examples

Example 1 — a first encounter with Megachasma alisonae

Start with the simplest possible case. Write down what Megachasma alisonae 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 Megachasma alisonae 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 Megachasma alisonae 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 Megachasma alisonae

In research: Megachasma alisonae 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 Megachasma alisonae 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: Megachasma alisonae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fossil taxa described in 2016, Megachasmidae, Prehistoric Chondrichthyes stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Megachasma alisonae 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 Megachasma alisonae in 20 minutes

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

Frequently asked questions

What is Megachasma alisonae in simple terms?

Megachasma alisonae is an extinct species of megamouth shark that lived during the Eocene (Priabonian, ca. 36 mya). It is the oldest fossil record of a megamouth shark.

Why does Megachasma alisonae 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 Megachasma alisonae?

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 Megachasma alisonae.