Tangasaurus

Key takeaways

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

Reference excerpt

Tangasaurus is an extinct genus of aquatic basal tangasaurid neodiapsid known from the Late Permian period (late Changhsingian stage) of Tanga, northeastern Tanzania. It contains a single species, Tangasaurus mennelli.

Etymology Tangasaurus was first described and named by Sidney H. Haughton in 1924 and the type species is Tangasaurus mennelli. The generic name is derived from the name of the Tanga Region in which the only known specimens were found, and Greek sauros, meaning "lizard". The specific name honors F. P. Mennell, the geologist who reported and collected the specimens of Tangasaurus.

Discovery Tangasaurus is known only from three syntypes which represent two individuals. The small individual, which is well preserved in two specimens (part and counterpart) and is known from a partial skull and a nearly complete postcranial skeleton, was designated as the lectotype of the genus. The part slab (showing the partial skull and postcranial) is hosted at the Bulawayo Museum, Zimbabwe, while the counterpart slab SAM 6231 (showing the other side of the postcranial) is hosted at the South African Museum, Cape Town. The third syntype, SAM 6232, represents a nearly complete postcranial skeleton from a larger individual, but it is poorly preserved. All specimens were collected by F. P. Mennell in 1922 at the Mizimbazi River near Tanga City, northeastern Tanzania. They were collected from the Ruhuhu Valley, in the middle part of the Tanga beds, dating to the late Changhsingian stage of the Lopingian series, about 252.5–251 million years ago. Although Mennell reported a presence of eight nearly complete individuals from that site, subsequent work couldn't find any evidence for the missing 6 individuals. Mennell's report, alongside some reptilian fragments that were discovered in 1913 and reported by Janensch (1927), are the only reptilian fossils currently known from the Tanga beds. Numerous well preserved specimens from various Late Permian localities of Madagascar were initially identified as Tangasaurus by Piveteau (1926). During that time the Mozambique Channel had just started to open. However, a reexamination of these specimens by Carroll (1981) and Currie (1982) has shown that they represent a different genus, Thadeosaurus, known only from Madagascar. Another specimen from Madagascar, MNHN 1908-32-57, was also tentatively referred to Tangasaurus. However, Currie (1980) found it to represent a new and distinct genus which he named Acerosodontosaurus.

Description Tangasaurus was described and named by Sidney H. Haughton in 1924 who found it to be a probable diapsid reptile that, because of the long, powerful, flattened tail, had become adapted for an aquatic existence. Contrary to Haughton, Piveteau (1926) considered Tangasaurus to be a primarily terrestrial animal. Following Nopcsa (1924), he considered it to be related to the Araeoscelis, Kadaliosaurus, Broomia and the "eosuchians" (a defunct clade that used to unite all diapsids more advanced than Araeoscelis) Saurosternon and Pleurosaurus. Described by Piveteau (1926), Hovasaurus boulei from Madagascar was considered to be related to Mesosaurus. Although not as specialized as Mesosaurus for living in the water, Piveteau noted its short neck, short manus, well developed haemal spines and slight pachyostosis of the ribs. Haughton (1930) restudied Piveteau's specimens from Madagascar, concluding that Tangasaurus (then included the Malagasy specimens) and Hovasaurus were allied and that both were diapsids. Tangasaurus was considered to be morphologically intermediate between Youngina and Hovasaurus which was recognized as an aquatic reptile due to its short forelimb and coracoid, small ossification and elongated body. Piveteau (1926) included Broomia, Saurosternon and Tangasaurus in the Tangasaurinae. After Haughton's paper (1930), Tangasaurus and Hovasaurus were usually included as the only representatives of the family Tangasauridae. The known specimens of Tangasaurus were redescribed by Philip J. Currie (1982). He diagnosed the genus on the basis of two autapomorphies: It possesses high and rectangular neural spines of the dorsal vertebrae and the height of neural spine of mid-caudal vertebra about 35% greater than length of associated centrum, and about 75% length of associated haemal arch and spine. The largest "tangasaurid" (sensu Currie, 1982) is Hovasaurus with an estimated maximum snout-vent length of about 30 cm (12 in). The largest specimen of Tangasaurus is 20% smaller than that, but its incomplete ossification suggests that larger specimens probably existed. Currie (1982) united to subfamilies within the Tangasauridae: Kenyasaurinae (that he named to include Kenyasaurus and Thadeosaurus) and Tangasaurinae (to include Tangasauridae sensu Haughton, 1930). He allied Tangasauridae and Youngina together within superfamily Younginoidea which he named. Currie (1980) named Acerosodontosaurus, and allied it with Younginoidea in the clade Younginiformes. More recent works that use phylogenetic analyses usually suggest that neither Younginoidea nor Younginiformes are monophyletic. Constanze Bickelmann, Johannes Müller and Robert R. Reisz (2009) redescribed Acerosodontosaurus and suggested an aquatic lifestyle for it. Their analysis is figured below, and it found support for two distinct families within "Younginiformes": the aquatic Tangasauridae, and the terrestrial Younginidae (in partial polytomy with Tangasauridae).

More resolved results were obtained by Robert R. Reisz, Sean P. Modesto and Diane M. Scott (2011) in their description of Orovenator. However, those results required the exclusion of the fragmentary taxa Galesphyrus, Kenyasaurus, Palaeagama and Saurosternon from their analysis. The cladogram below shows Tangasaurus phylogenetic position among other neodiapsids following Reisz et al., 2011.

References

Worked examples

Example 1 — a first encounter with Tangasaurus

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

In research: Tangasaurus 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 Tangasaurus 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: Tangasaurus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Changhsingian life, Diapsids, Fossil taxa described in 1924, so understanding it makes those chapters shorter.
In everyday life: Look for Tangasaurus 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.

How to study Tangasaurus in 20 minutes

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

Frequently asked questions

What is Tangasaurus in simple terms?

Tangasaurus is an extinct genus of aquatic basal tangasaurid neodiapsid known from the Late Permian period (late Changhsingian stage) of Tanga, northeastern Tanzania. It contains a single species, Tangasaurus mennelli.

Why does Tangasaurus 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 Tangasaurus?

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 Tangasaurus.