Question 1

How do you say Temporal Fenestra?

Accepted Answer

Say it like this: TEM-por-al feh-NES-tra. The first word, temporal, has the stress on the first syllable, TEM, and sounds like the word you use for a temporary situation. The second word, fenestra, puts the stress on the second syllable, NES, and rhymes loosely with orchestra. Put them together: TEM-por-al feh-NES-tra. Once you say it a few times it rolls off the tongue naturally.

Question 2

What does Temporal Fenestra mean?

Accepted Answer

Temporal fenestra is Latin for skull window at the temple. The word fenestra means window in Latin, and temporal refers to the temple region of the skull, the area behind your eye and toward the back of your head. So scientists are literally calling these features skull windows, because they are openings framed by bone just like windows are openings framed by a wall. The name is extremely descriptive once you know the Latin.

Question 3

What is a temporal fenestra in dinosaurs?

Accepted Answer

A temporal fenestra is one of the openings in the skull of a dinosaur, located behind the eye socket in the temple region of the head. Most dinosaurs had two of these openings on each side of their skull, an upper one called the supratemporal fenestra and a lower one called the infratemporal fenestra. These windows were framed by arching struts of bone and served as attachment points for powerful jaw muscles. They also reduced the overall weight of the skull significantly.

Question 4

Why do dinosaur skulls have so many holes in them?

Accepted Answer

Dinosaur skulls have multiple openings because evolution favored skulls that were strong but lightweight. Solid bone is extremely heavy, so over millions of years dinosaur lineages evolved a series of fenestrae, or windows, that removed unnecessary bone while keeping structural arches that bore the mechanical loads. The temporal fenestrae behind the eye were the largest of these openings in most dinosaurs. The result was a skull that functioned like a structural framework rather than a solid box, saving enormous amounts of weight and energy.

Question 5

Did T. rex have temporal fenestrae?

Accepted Answer

Yes, Tyrannosaurus rex had prominent temporal fenestrae, and they were huge. The supratemporal fenestrae on the top of a T. rex skull are large enough for a person to put their fist inside in a full-grown specimen. These openings anchored the massive temporalis jaw muscles that gave T. rex one of the most powerful bites of any land animal ever measured, estimated at over 8,000 pounds of force by some studies. Without those skull windows providing muscle attachment area, that devastating bite would simply not have been possible.

Question 6

Do any animals alive today still have temporal fenestrae?

Accepted Answer

Yes, many living animals still have temporal fenestrae because dinosaurs never truly went extinct: birds are living dinosaurs and they are diapsids with the evolutionary remnants of two temporal fenestrae on each side of the skull. Crocodilians, the closest living relatives of birds among non-avian reptiles, have very clear temporal fenestrae. Lizards and snakes also retain them in various forms. Even humans have a version: the temporal fossa on the side of your skull, the slight hollow you can feel behind your eye, is the evolutionary legacy of the synapsid temporal fenestra in our mammal-like reptile ancestors.

Question 7

What is the difference between a supratemporal and infratemporal fenestra?

Accepted Answer

The supratemporal fenestra is the upper of the two openings, sitting on the top surface of the skull and facing upward. The infratemporal fenestra, also called the lateral temporal fenestra, is the lower opening and faces sideways, so you can see it clearly when looking at a dinosaur skull from the side. Both are present in diapsid animals, which includes all dinosaurs. The supratemporal fenestra was typically more important for jaw muscle attachment in large predatory dinosaurs, while the infratemporal fenestra contributed more to the overall lightweight architecture of the skull.

Question 8

What is a diapsid and why does it matter for temporal fenestrae?

Accepted Answer

A diapsid is an amniote animal defined by having two temporal fenestrae on each side of the skull. The word diapsid comes from the Greek words for two and arch. All dinosaurs, including birds, are diapsids, as are all living lizards, snakes, and crocodilians. The diapsid condition is one of the most important defining features in vertebrate classification, and it has been used by paleontologists since the early twentieth century to organize the reptile family tree. Identifying temporal fenestrae in a fossil animal is often one of the first steps in figuring out where it belongs evolutionarily.

Question 9

How do scientists study temporal fenestrae in fossils?

Accepted Answer

Scientists study temporal fenestrae in fossils using several methods. The most traditional approach is physical preparation, carefully removing rock matrix from around the skull to expose the fenestrae and the bones framing them. Modern researchers increasingly use CT scanning to digitally reconstruct skulls in three dimensions without damaging the specimen. This allows them to measure the size and shape of the fenestrae precisely, model the jaw muscles that filled them, and estimate bite force. Comparative studies published in peer-reviewed journals then compare these measurements across dozens of species to track how temporal fenestrae evolved over time.

Question 10

Are temporal fenestrae the same as the holes in the nose of a dinosaur skull?

Accepted Answer

No, temporal fenestrae are different from nasal openings. Dinosaur skulls had several different types of openings, each with its own name and function. The naris is the nasal opening at the front of the snout. The orbit is the eye socket. The antorbital fenestra is an opening between the eye and the nose that is unique to archosaurs. The temporal fenestrae are specifically the openings behind the eye in the temple region of the skull. Keeping track of which hole is which is actually an important part of how paleontologists identify and classify fossil skulls.

Question 11

When did temporal fenestrae first evolve?

Accepted Answer

Temporal fenestrae first evolved during the Permian period, more than 250 million years ago, and possibly even earlier in the late Carboniferous period around 300 million years ago. The earliest diapsids, the group with two temporal fenestrae, appear in the fossil record in the late Carboniferous. These small lizard-like animals were the distant ancestors of all dinosaurs, birds, lizards, snakes, and crocodilians alive today. The evolutionary split between synapsids, which have one temporal fenestra and eventually led to mammals, and diapsids happened very early in amniote evolution, making temporal fenestrae one of the oldest defining features in vertebrate classification.

Question 12

Can you feel a temporal fenestra on your own head?

Accepted Answer

Humans do not have a true temporal fenestra in the way dinosaurs did, because we are mammals descended from synapsids, which only ever had one lower temporal opening rather than two. However, you can feel the region where our evolutionary ancestors had that opening: press your fingertips gently to the side of your head behind your eye socket and you will feel the temporal fossa, a slight depression in your skull. The temporalis muscle, the large muscle you can feel moving when you chew, fills this area in humans just as jaw muscles filled the temporal fenestrae in dinosaurs. So in a real sense, your chewing muscle is an echo of dinosaur skull evolution.

Question 13

Why do some dinosaur skulls look so lightweight and open?

Accepted Answer

Dinosaur skulls look lightweight and open precisely because of features like temporal fenestrae. Over millions of years, natural selection favored skulls that balanced structural strength with minimal weight. Bone is metabolically expensive to grow and heavy to carry, so any opening that could be made without compromising the skull's ability to handle bite forces and other stresses was advantageous. The temporal fenestrae were the largest of these openings, but dinosaurs also had antorbital fenestrae, mandibular fenestrae in the lower jaw, and other openings. The result was a skull that looked almost skeletal in its openness but was biomechanically sophisticated and highly efficient.

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