Kwanasaurus

Key takeaways

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

Reference excerpt

Kwanasaurus is an extinct genus of silesaurid dinosauromorph reptiles from the Late Triassic of Colorado. It is known from a single species, Kwanasaurus williamparkeri. Kwanasaurus had a deeper, stronger skull and greater specialization for herbivory compared to other silesaurids. It also possessed many unique characteristics of the snout, ilium, and lower part of the femur. It was described along with new specimens of Dromomeron from the Eagle Basin, the northernmost extent of the Chinle Formation.

Discovery Kwanasaurus hails from Triassic deposits in the Eagle Basin surrounding the town of Eagle, Colorado. This area contains the most northern exposures of the Chinle Formation, which is famous for its Late Triassic fossils of dinosaurs and other reptiles. Tentative terrestrial reptile biostratigraphy estimates that the Eagle Basin fossils, which were preserved in red siltstone, belong to the Revueltian biozone of the mid to late Norian stage of the Triassic, 215-207 million years ago. The holotype of Kwanasaurus is a partial silesaurid maxilla, DMNH EPV.65879. All other silesaurid maxillae recovered from the area seem to represent the same taxon, indicating that Kwanasaurus was likely the only silesaurid from the Eagle Basin. With this in mind, all other Eagle Basin fossils resembling those of silesaurids have been referred to the taxon. These include multiple dentaries, teeth, ilia, femora, and a humerus. Dinosauromorph-like tibia and scapulae from the area may also belong to Kwanasaurus, though they have not been referred to the genus due to lacking any clear silesaurid features. Kwanasaurus was named in a 2019 paper by Jeffrey W. Martz and Bryan J. Small, along with the description of new Dromomeron material. The genus name incorporates kwana, the Ute name for eagle. The specific name commemorates paleontologist Bill Parker.

Description

Skull

The maxilla is much deeper and more robust in Kwanasaurus than in any other silesaurid. There are replacement pits on the inner edge of the tooth row similar to those of thyreophorans, and smaller and more numerous pits on the outer surface of the maxilla. Five of the replacement pits at the midlength of the bone are set in a groove, a trait also present in Silesaurus and silesaurid skull material from the Ntawere Formation. The front of the maxilla is similar to that of Lewisuchus and Silesaurus, with a triangular premaxillary facet and thick, sharp vomerine flange. The ascending process of the maxilla is a thin, anteroposteriorly wide, and steeply-rising prong, and the antorbital fossa has a concave lower edge, both like Silesaurus. The inner surface of the maxilla has a thick medial flange, which droops down to the tooth row as a smooth triangular blade. This medial flange is unique to Kwanasaurus among silesaurids (and Triassic dinosauromorphs in general), and likely extended the maxilla's connection with the palate behind the vomer. The rear portion of the holotype maxilla is characteristically complex and similar to that described for Plateosaurus. These complex traits include a posterolateral flange which likely shielded part of the jugal, a pair of deep dorsomedial grooves (likely articulating with the lacrimal and jugal), and a broad groove behind the medial flange which likely articulated with the palatine.

Lower jaw bones referred to Kwanasaurus include DMNH EPV.63136, one of the most complete dentaries found for any silesaurid. As in other sulcimentisaurians, the meckelian groove is positioned close to the lower edge of the jaw and the teeth are constricted at the root. The front tip of the dentary is pointed, toothless, and has a lateral groove akin to that of Silesaurus and Sacisaurus, along with several medial grooves. Further back, the dentary is relatively deep and develops a lateral ridge similar to one reported for Diodorus and Eucoelophysis. The pattern of pitting and holes on the outer surface of the dentary also resembles those taxa. The tooth row is edged by a medial groove connecting a series of replacement pits; above the groove the bone is inset similar to the case in Silesaurus, Eucoelophysis, and Technosaurus. Kwanasaurus is the only silesaurid to preserve data on the mandibular fenestra. This hole in the jaw was triangular, edged from below by a posteroventral process of the dentary which also overlapped a partial angular. The dentary's posterodorsal process is sharp along its upper edge and notched along its lower edge.

Teeth Teeth of Kwanasaurus have been found both as isolated material and within maxillae and dentaries. Isolated teeth are leaf-shaped, with coarse denticles, slightly flattened sides, and crown tips more than halfway towards the rear of the tooth. The lingual (tongue) side of the tooth has a thick vertical ridge covered in striations. Sacisaurus, Eucoelophysis, and possibly Technosaurus are the only other silesaurids known to possess similar teeth, although leaf-shaped teeth are also common in various other herbivorous archosaurs. In some of the maxilla, the teeth are short and swollen (almost round in cross section) and become smaller towards the rear of the bone. The dentary teeth are similar but more asymmetrical. The middle of the dentary has the largest and most denticulate teeth in the jaw. There are 12 maxillary teeth and 14 dentary teeth. These teeth extend further back in the skull than most silesaurids, as is the case in Lewisuchus, but they are not as numerous as those of that taxon. Like other silesaurids, Kwanasaurus has ankylothecodont tooth implantation, meaning the teeth are set in sockets but also fused to the surrounding bone. At least in the maxilla, Kwanasaurus has a complex pattern of tooth replacement. This pattern involves replacement teeth being formed along the lingual edge of the tooth row, shifting outwards (at which point the original tooth's attachment dissolves and the tooth detaches), fusing to the leftover socket and leaving behind a replacement pit. The tooth row has alternating empty and full sockets, indicating that adjacent teeth were never replaced at the same time. This contrasts with Silesaurus and Technosaurus (which sometimes have several adjacent teeth replaced at once), but resembles the condition in some specimens of Sacisaurus, Diodorus, and Asilisaurus.

Forelimbs

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Kwanasaurus

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

In research: Kwanasaurus 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 Kwanasaurus 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: Kwanasaurus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chinle fauna, Fossil taxa described in 2019, Norian reptiles, so understanding it makes those chapters shorter.
In everyday life: Look for Kwanasaurus 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 Kwanasaurus in 20 minutes

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

Frequently asked questions

What is Kwanasaurus in simple terms?

Kwanasaurus is an extinct genus of silesaurid dinosauromorph reptiles from the Late Triassic of Colorado. It is known from a single species, Kwanasaurus williamparkeri.

Why does Kwanasaurus 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 Kwanasaurus?

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 Kwanasaurus.