biology

Tannudiscus

Tannudiscus 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 Tannudiscus rather than just read about it. In short: Tannudiscus Pokrovskaya (1959) is a genus of eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida (Salter 1864).

Key takeaways

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

Reference excerpt

Tannudiscus Pokrovskaya (1959) is a genus of eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida (Salter 1864). It lived during the late Lower Cambrian, with remains found in Canada (Newfoundland), China (Gansu), The United Kingdom (England), and the Russian Federation (Tuva, Gorno-Altayskaya). TYPE SPECIES: T. tannulaicus Pokrovskaya, 1959.

Taxonomy The Weymouthiid family shows a trend of shortening the occipital ring. In Chelediscus and Tannudiscus the occipital ring is entirely obliterated as in the Agnostina suborder. Tannudiscus has some other characters it shares with the Agnostina, such as a glabella consisting of two lobes and the occipital ring divided into basal glabellar lobes. Both the glabella and pygidial axis are isolated from the border furrow, and the latter is undivided. It is therefore considered likely that the Agnostina descended directly from a species assignable to Tannudiscus. The earliest known Agnostina is Archaeagnostus (Peronopsidae). According to Cotton and Fortey (2005) Tannudiscus is polyphyletic.

Description Tannudiscus lacks eyes and has a thorax of three segments. The glabella almost touches the anterior border and consists of two inflated lobes, the frontal one slightly wider than the posterior lobe—a characteristic that is further developed in the Condylopygidae. Posterior glabellar lobe lacks a spine. The occipital ring is formed into two basal lateral lobes. The border is convex, moderately wide, more so in front of the glabella and extends to rear of the glabella in some species. Pygidial axis is conical, with seven or eight rings, and may or may not reach posterior border furrow. The furrows defining the axial rings are indistinct or obsolete. Pygidial border is almost flat, but similar in width to the cephalic border.

Distribution T. tannulaicus is known from the Lower Cambrian of the Russian Federation (Toyonian (= Stage 4, upper of two stages subdividing the un-named Cambrian Series 2), Shivelikskaya Suite, Tuva, Shivelik-Khem River, eastern Tannu-Ola Mountains). T. balanus was originally described in the Lower Cambrian of England. Holotype is A 57119, held at the Sedgwick Museum of Earth Sciences, University of Cambridge; collected by Rushton from about 450m above base of the Purley Shale Formation, Camp Hill, St. Paul's Church, Stockingford, Nuneaton, Warwickshire, England [Closest ICS interval: Cambrian Series 3 – Terreneuvian Epoch]. The species also occurs in the Toyonian, upper Redland Cove member, Brigus Formation of southeastern Newfoundland and also has been found in the Lower Cambrian of the Russian Federation (Russian-Kazakhian Botomian Stage, Sanashtykgolskogo horizon, Shashkunarskaya suite). T. conicus has been recovered from the late Lower Cambrian of China (Huocheng Formation, Borohoro district). T. extensus is present in the Middle Cambrian of Russian Federation (Amgaian, Berikul Formation, Kiya River section, Kuznetsk Alatau).

References

Worked examples

Example 1 — a first encounter with Tannudiscus

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

In research: Tannudiscus 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 Tannudiscus 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: Tannudiscus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Agnostida genera, Cambrian genus extinctions, Cambrian trilobites, so understanding it makes those chapters shorter.
In everyday life: Look for Tannudiscus 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 Tannudiscus in 20 minutes

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

Frequently asked questions

What is Tannudiscus in simple terms?

Tannudiscus Pokrovskaya (1959) is a genus of eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida (Salter 1864).

Why does Tannudiscus 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 Tannudiscus?

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 Tannudiscus.