Thread by @JacquelynGill

Good morning, Planeteers! For today’s #MaleAPlanet quiz, spot the (likely) lie:

A) The dinosaur Anchiornis had brown, grey, black and white 🪶.

B) 🦣 were matriarchal, like modern elephants.

C) T. Rex “ran” ~5 m/s (11 mph) 🦖.

D) Giant ice age 🦫 built giant ice age dams.

Today’s quiz is inspired by all the creative ways we can infer something about the behavior of extinct organisms based on clues in the fossil record.

Whoops, that was supposed to be #MakeAPlanet!

It's answer time! I love this question, because there's so much that we can learn about behavior from traces in the fossil record. For a lot of these, you might at first think "there's no way we could know this -- we weren't there!"

And yet...

Let's start with Anchiornis. "What colors were dinosaurs?" is a great example of things we once said we could never know, but now often can. Thanks to microscopic structures in feathers called melanosomes, (which fossilize!) we can tell what colors many dinosaurs were!

From shiny blue-black feathers like corvids, to bright colors like hummingbirds, we can now fill in the palettes of the Cretaceous with more than our imaginations. smithsonianmag.com/science-nature…

What about matriarchal mammoths? How could we possibly know that? There are a few lines of evidence: 1) in "death traps" like the Mammoth Site or La Brea, remains are disproportionately juvenile males, which is consistent with them losing the herd's wisdom when they go solo.

2) We can tell the sex of animals from their fossilized trackways (size, gait), and in cases where groups of tracks are found together, we can recreate family structures. smithsonianmag.com/science-nature…

3) Mammoth tusks have growth rings, like trees! Female tusks tend to have evenly spaced rings on average, except when they have babies (which uses resources). Males have even rings until puberty, when they become much closer, signaling a period of poor diets as "teenagers."

Taken together, and compared with modern elephants (which mammoths and mastodons were close cousins of), the evidence points to mammoths having matriarchs-- including cultural knowledge about landscapes and resources that was passed down through generations.

Tyrannosaurus rex's speed has been debated, with some estimates as high as 20 m/s. These are based on trackways (imprint depth, distance between footprints), and biomechanical models. A 2002 study found that to run that fast, 86% of T. rex's body mass would have been in its legs!

Some of the more recent studies suggest a slower running speed closer to 5 m/s, at least for adults. And a study last year that focused on T. rex's tail found an average walking speed of ~3 mph. smithsonianmag.com/smart-news/new…

But if the slower running speeds are accurate, does that mean T. rex was a scavenger, not a ferocious predator? It was probably both, based on extensive research, as @Laelaps has written...and that's been widely accepted for a couple of decades now. nationalgeographic.com/science/articl…

So if A, B, and C are correct, that means D is the lie. As much as I want these big, black-bear-sized giant beavers to have been ice age dam-builders, there's no evidence that they did. And their teeth appear to be poorly suited to chewing on wood (though they were rodents!).

There have been giant ice age dams, but these were caused by ice sheets damming meltwater, which would burst in massive, catastrophic floods! pbs.org/wgbh/nova/arti…

If you'd like to learn more about function and behavior in the fossil record, this is a pretty accessible review article that has some fun and lovely examples. journals.plos.org/plosbiology/ar…

Do you get a thrill thinking about ancient beasts and their fascinating lives? Wishing I would just stop posting these silly quizzes already? Back @MakeAPlanetPod, so we can bring the past to you, instead of testing you on it every day! kickstarter.com/projects/makea…