biology

Predentary

Predentary 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 Predentary rather than just read about it. In short: A predentary is an ossification situated on the front of the lower jaw, which extended the dentary (the main lower jaw bone). A predentary bone has evolved independently in two groups of teleost fish, Istiophoridae and Saurodontidae, and two dinosaur groups, ornithischians and ornithuromorph birds.

Key takeaways

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

Reference excerpt

A predentary is an ossification situated on the front of the lower jaw, which extended the dentary (the main lower jaw bone). A predentary bone has evolved independently in two groups of teleost fish, Istiophoridae and Saurodontidae, and two dinosaur groups, ornithischians and ornithuromorph birds. A predentary is found in all but perhaps the earliest ornithischian dinosaurs. Its occurrence led Othniel Marsh to propose naming the group Predentata, though this is now considered a synonym of Ornithischia. The predentary coincided with the premaxilla in the upper jaw. Together, they formed a beak-like apparatus used to clip off plant material. In ceratopsian dinosaurs, it opposes the rostral bone. The predentary would have allowed the dentaries to move slightly independently of each other, aiding chewing. The toothless, beaked tip of the dentary in silesaurids may have been a predecessor of the ornithischian predentary. The avian predentary arose in the clade Ornithuromorpha, and is absent from earlier bird lineages such as enantiornitheans and Archaeopteryx. It has been interpreted as a sesamoid bone. Members of Neornithes, the group containing all modern birds, lack a predentary, unlike other ornithuromorphs, possibly because the fusion of the mandibular symphysis and loss of teeth rendered the predentary unnecessary. Due to the independent origins of the predentary in ornithischians and birds, the avian predentary has alternatively been called the intersymphyseal ossificiation, although this term is not entirely appropriate because it is not strictly intersymphyseal in position. An ossified predentary has arisen in two lineages of fish, the extinct Saurodontidae and the extant Istiophoridae (marlin), and a cartilaginous pre-mandibular element occurs in several other groups. The istiophorid predentary differs from other predentaries in bearing denticles.

References

Illustrations

Worked examples

Example 1 — a first encounter with Predentary

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

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

Affiliate

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

How to study Predentary in 20 minutes

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

Frequently asked questions

What is Predentary in simple terms?

Why does Predentary 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 Predentary?

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 Predentary.