science

Metriacanthosauridae

Metriacanthosauridae is a science 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 Metriacanthosauridae rather than just read about it. In short: Metriacanthosauridae (Greek for "moderately-spined lizards") is an extinct family of allosauroid theropod dinosaurs that lived in Europe and Asia from the Middle Jurassic to the Early Cretaceous. The family is split into two subgroups: Metriacanthosaurinae, which includes dinosaurs closely related to Metriacanthosaurus, and another group composed of the close relatives of Yangchuanosaurus.

Key takeaways

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

Reference excerpt

Metriacanthosauridae (Greek for "moderately-spined lizards") is an extinct family of allosauroid theropod dinosaurs that lived in Europe and Asia from the Middle Jurassic to the Early Cretaceous. The family is split into two subgroups: Metriacanthosaurinae, which includes dinosaurs closely related to Metriacanthosaurus, and another group composed of the close relatives of Yangchuanosaurus. Metriacanthosaurids are considered carnosaurs, belonging to the Allosauroidea superfamily. The group includes species of large range in body size. Of their physical traits, most notable are their neural spines. The records of the group are mostly confined to Asia, though Metriacanthosaurus is known from Europe. Metriacanthosauridae is used as a senior synonym of Sinraptoridae.

Diagnostic traits

Metriacanthosaurids share the following unambiguous synapomorphies among allosauroids:

A short or absent anterior ramus of the maxilla (also found in carcharodontosaurids and piatnitzkysaurids). The laterosphenoid articulated on the frontal and postorbital. A squamosal without constriction of the lower temporal fenestra. (also found in megalosauroids) A flange on the squamosal covering the quadrate head laterally. A well-defined longitudinal groove on the lateral side of the dentary housing a row of neurovascular foramina. Broad, well developed spinopost-zygapophyseal lamina on the axis. A manus shorter than the forearm. Subrectangular and sheet-like neural spines of middle caudal vertebrae. A manus without digit V or the phalanges of digit IV (also found in neovenatorids). A heart-shaped cross section of the ilium's paired midshafts (also found in coelophysids). Fused distal end of the ischium (also found in neovenatorids and basal tetanurans). Metriacanthosaurids share the following dental synapomorphies among theropods:

surface centrally positioned on the labial surface of the crown roughly flattened in lateral teeth irregular and non-oriented enamel surface texture Metriacanthosaurines share the following synapomorphies among metriacanthosaurids:

The anteroventral border of the maxillary antorbital fenestra being demarcated by a raised ridge (also found in Eoraptor, coelophysids, Masiakasaurus, Marshosaurus, and Compsognathus). A pronounced ventral keel on the anterior dorsal vertebrae (also found in Condorraptor, Piatnitzkysaurus, Carcharodontosaurus and many megalosaurians). A straight posterior margin of the iliac postacetabular process. The angle between the long axes of the pubic shaft and boot being less than 60 degrees. A ventrally curved ischial shaft (also found in coelophysids, Eustreptospondylus, Afrovenator, Megalosaurus and Compsognathus). A bulbous fibular crest on the tibia (also found in Sinosaurus).

Classification Carrano, Benson & Sampson (2012) noted that the name Metriacanthosauridae should be used as it has priority over Sinraptoridae. Cladistically, Sinraptoridae had been latest defined in 2005 by Paul Sereno as the most inclusive monophyletic group that contains Sinraptor dongi and all species closer to Sinraptor than to either Allosaurus fragilis, Carcharodontosaurus saharicus, or the house sparrow (Passer domesticus). Furthermore, the 2012 study named a new subfamily Metriacanthosaurinae to include all metriacanthosaurids more closely related to Metriacanthosaurus than to Yangchuanosaurus. A much larger phylogenetic analysis found Xuanhanosaurus, previously considered a basal megalosauroid, to be the basalmost metriacanthosaurid. Both Poekilopleuron and Lourinhanosaurus were recovered outside the family, and many taxa within the Metriacanthosauridae were in polytomy. However, the positions of Xuanhanosaurus and Poekilopleuron were very unstable, and their exclusion from the analysis gave a more resolved and stable cladogram. The cladogram presented here follows that study.

Palaeobiogeography Metriacanthosauridae fossils have only been found in modern Europe and Asia, parts of the prehistoric landmass Laurasia. The biogeographic origin of metriacanthosaurids based on phylogenetic analysis is suggested to be South-East Asia, specified as "Chinese provinces of Sichuan and Yunnan and areas south of this", and the earliest known taxa are Shidaisaurus from southern China and Alpkarakush from Kyrgyzstan. Fragmentary remains of allosauroids from the late Middle-early Late Jurassic Marnes de Dives in northern France bear close similarities to metriocanthosaurids, and may belong to members of the group.

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with Metriacanthosauridae

Start with the simplest possible case. Write down what Metriacanthosauridae claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Metriacanthosauridae 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 Metriacanthosauridae 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 Metriacanthosauridae

In research: Metriacanthosauridae appears in science 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 Metriacanthosauridae 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: Metriacanthosauridae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dinosaur families, Metriacanthosauridae, so understanding it makes those chapters shorter.
In everyday life: Look for Metriacanthosauridae 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 Metriacanthosauridae in 20 minutes

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

Frequently asked questions

What is Metriacanthosauridae in simple terms?

Why does Metriacanthosauridae matter?

Because it connects several science 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 Metriacanthosauridae?

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 Metriacanthosauridae.