biology

Psephophorus

Psephophorus 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 Psephophorus rather than just read about it. In short: Psephophorus is an extinct genus of sea turtle that lived from the Oligocene to the Pliocene. Its remains have been found in Europe, Africa, North America, and New Zealand.

Key takeaways

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

Reference excerpt

Psephophorus is an extinct genus of sea turtle that lived from the Oligocene to the Pliocene. Its remains have been found in Europe, Africa, North America, and New Zealand. It was first named by Hermann von Meyer in 1847, and contains eight species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis, P. californiensis, P. rupeliensis, P. scaldii, and P. terrypratchetti. Psephophorus is the only Miocene dermochelyid turtle found in Europe. One species of Psephophorus could measure up to ten feet in length.

Discovery and identification

Von Meyer originally named Psephophorus in 1846. At first he was unable to identify the creature beyond its dermal plates, but when he later received a drawing he was able to describe the specimen, which was then in Pressburg, as a fragment of a carapace, which contained seventy bones. In 1879, H. G. Seeley was asked to study the Psephophorus specimen by Franz Ritter von Hauer, the Director of the Austro-Hungarian Imperial and Royal Geological Survey. Up until then, the specimen's identity had been undeterminable, with even Seeley describing it at first to seem like "the dermal covering of an Edentate closely allied to the Armadilloes." Seeley examined some bone fragments and concluded the specimen was that of a reptilian creature, furthermore a chelonid. It also proved to be more closely related to Sphargis than any other type in the Chelonian order.

Relation to modern leatherback sea turtles For a long time, modern leatherback sea turtles (Dermochelys) were believed to be descended directly from Psephophorus, specifically the species P. polygonus. However, a 1996 analysis by Wood et al. proved that most of the taxa in the two genera were not connected, meaning Psephophorus could not be a direct ancestor of the modern leatherbacks. The platelets on Psephophorus are quite similar to those on Dermochelys, despite differences in outer morphology and size. The platelet comprises an external compact layer and an internal zone of cancellous bone.

Species

Psephophorus polygonus is the type species, and was discovered by von Meyer in 1846. Fossils of the species have shown bony, carapacial ridges, adjacent, small and polygonal bony ossicles which measure about 22 × 25 mm. When the ossicles extend further along the longitudinal axis, their size increases up to an average of 33 × 41 mm. Psephophorus calvertensis was first named by Palmer in 1909. It was so named for being found in the Calvert Formation. P. calvertensis is a rarely found specimen. Psephophorus eocaenus was first named by Andrews in 1901. Psephophorus californiensis was first named by Gilmore in 1937. Psephophorus terrypratchetti was discovered in the 1990s by Richard Köhler in New Zealand and named in 1995 after the author Terry Pratchett, who wrote a series of fantasy books set on a world carried on the back of a giant turtle. This species reached 2.3–2.5 m (7.5–8.2 ft) in body length which is more than 80% bigger than P. eocaenus.

Illustrations

Worked examples

Example 1 — a first encounter with Psephophorus

Start with the simplest possible case. Write down what Psephophorus 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 Psephophorus 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 Psephophorus 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 Psephophorus

In research: Psephophorus 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 Psephophorus 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: Psephophorus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cenozoic reptiles of Europe, Cenozoic reptiles of North America, Dermochelyidae, so understanding it makes those chapters shorter.
In everyday life: Look for Psephophorus 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 Psephophorus in 20 minutes

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

Frequently asked questions

What is Psephophorus in simple terms?

Psephophorus is an extinct genus of sea turtle that lived from the Oligocene to the Pliocene. Its remains have been found in Europe, Africa, North America, and New Zealand.

Why does Psephophorus 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 Psephophorus?

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 Psephophorus.