biology

Idmonarachne

Idmonarachne 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 Idmonarachne rather than just read about it. In short: Idmonarachne is an extinct genus of arachnids, containing one species, Idmonarachne brasieri. It is related to uraraneids and spiders.

Key takeaways

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

Reference excerpt

Idmonarachne is an extinct genus of arachnids, containing one species, Idmonarachne brasieri. It is related to uraraneids and spiders.

Fossil A fossil assigned to this genus was found at Montceau-les-Mines, France, in ironstone concretion deposits of Late Carboniferous (Stephanian) age, about 305–299 million years old. Montceau fossils are generally preserved in such a way that fine details can be observed and three-dimensional analysis is possible. In the case of Idmonarachne, computerized tomography was used to construct a "virtual fossil".

Description The total body length of the fossil is around 10.5 mm, with the preserved part of the carapace of the cephalothorax about five mm long and the opisthosoma (abdomen) about six mm long. The eight walking legs are more-or-less uniform in appearance, with the fourth leg longest at about 8.5 mm and the first shortest at about 6.5 mm. The legs terminate in at least two claws. The two pedipalps are slightly shorter than the legs, at just under four mm long. The chelicerae are shaped like a clasp-knife, i.e. with the fang at the end folding back into the part to which it is attached. The opisthosoma shows at least seven sections on the upper surface (tergites), each with a flattened W-shaped profile composed of a wider upwardly curved central plate and two side plates. The lower surface of the opisthosoma bears eight visible plates. No spinnerets, telson or terminal spike (flagellum) are present.

Taxonomy The fossil was placed in a new genus, Idmonarachne, as the species I. brasieri. The genus name is based on the Arachne myth in which Idmon is her father, and is intended to show the position of the genus as a close relative of spiders. The species name honours Martin David Brasier for his contributions to the study of ancient life. The authors did not place the genus in a family or order.

Phylogeny Based on its overall morphology, Idmonarachne was considered to belong to the Serikodiastida, a clade of tetrapulmonate arachnids capable of making and using silk, although the presence of silk-producing spigots was not demonstrated. Like uraraneids, it lacked spinnerets, but it did not have a flagellum, thus resembling spiders. A cladogram placed Idmonarachne between uraraenids and spiders:

The Late Carboniferous appears to be a time when there was a greater diversity of tetrapulmonate arachnids.

References

Illustrations

Worked examples

Example 1 — a first encounter with Idmonarachne

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

In research: Idmonarachne 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 Idmonarachne 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: Idmonarachne is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carboniferous France, Carboniferous arachnids, Carboniferous arthropods of Europe, so understanding it makes those chapters shorter.
In everyday life: Look for Idmonarachne 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 Idmonarachne in 20 minutes

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

Frequently asked questions

What is Idmonarachne in simple terms?

Idmonarachne is an extinct genus of arachnids, containing one species, Idmonarachne brasieri. It is related to uraraneids and spiders.

Why does Idmonarachne 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 Idmonarachne?

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 Idmonarachne.