biology

Illaenus

Illaenus 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 Illaenus rather than just read about it. In short: Illaenus is a genus of trilobites from Russia and Morocco, from the middle Ordovician. Species included in this genus can reach a length of about 57 millimetres (2.2 in).

Key takeaways

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

Reference excerpt

Illaenus is a genus of trilobites from Russia and Morocco, from the middle Ordovician. Species included in this genus can reach a length of about 57 millimetres (2.2 in). They are without glabella and without articulation of the tail. The cephalon has a high profile and recurved genal spines. Eyes are distant from the axis of the head, situated nearer to the edge.

Selected species This genus includes about 50 species:

†Illaenus alveatus Raymond 1925 †Illaenus auriculatus Ross Jr. & Barnes 1967 †Illaenus bayfieldi Billings 1859 †Illaenus bucculentus Whittington 1963 †Illaenus consimilis Billings 1865 †Illaenus consobrinus Billings 1865 †Illaenus crassicauda Wahlenberg 1826 †Illaenus fraternus Billings 1865 †Illaenus gelasinus Whittington 1965 †Illaenus lacertus Whittington 1954 †Illaenus marginalis Raymond 1925 †Illaenus oscitatus Fortey 1980 †Illaenus slancyensis Krylov 2016 †Illaenus spiculatus Whittington 1963 †Illaenus tauricornis Kutorga 1848 †Illaenus tumidifrons Billings 1865 †Illaenus utahensis Hintze 1952 †Illaenus welchi Loch & Ethington 2017

See also Ordovician fauna of Putilovo village

References

Yvonne Howells, "Ordovician Trilobites of St. Petersburg Region"

External links

Russian Trilobites Saint Petersburg Paleontological Laboratory Archived 2012-03-24 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Illaenus

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

In research: Illaenus 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 Illaenus 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: Illaenus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bromide Formation, Corynexochida genera, Corynexochida stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Illaenus 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Illaenus” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Illaenus in 20 minutes

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

Frequently asked questions

What is Illaenus in simple terms?

Illaenus is a genus of trilobites from Russia and Morocco, from the middle Ordovician. Species included in this genus can reach a length of about 57 millimetres (2.2 in).

Why does Illaenus 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 Illaenus?

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 Illaenus.