Did Dreadnoughtus Really Have Air Sacs?

Live Science

Beloved sauropod Dreadnoughtus is featured in the Apple TV+ show PREHISTORIC PLANET, episode 2 "Deserts." Paleontologist Dr. Kenneth Lacovara discusses their presentation and how accurate the dinosaurs were depicted.

Transcript

00:00It was quite a long scene of Dreadnoughtus.

00:03Here they are.

00:05A fight scene.

00:06It was a fight scene in this territorial battle

00:11between males.

00:12And I think this was actually kind of based on our science,

00:16because what we found with the two Dreadnoughtus individuals

00:20is that the much larger one, the 65-ton one,

00:24was osteologically, that means its bones,

00:26was osteologically quite young.

00:29You might even think of it as a teenager

00:31who was growing rapidly at the time of its death.

00:34Whereas the one that we found that was one-third smaller,

00:38osteologically, was much, much older.

00:41And so where do you find this in animals today?

00:43Where you find older, smaller individuals

00:46and younger, bigger individuals?

00:47That's in species where you have sexual dimorphism,

00:51where the two sexes are of different sizes.

00:55And usually that happens

00:56where you have male-dominated sexual selection,

00:59which means that two alpha males

01:01are going to compete with each other

01:03to control a territory or a group of females.

01:06There's also female-dominated sexual selection.

01:09That's where you see the males showing off

01:11with all kinds of colors and doing fancy tricks

01:14and buying Corvettes and things like that.

01:17And so with Dreadnoughtus, we have just a hint

01:21that we have sexual dimorphism.

01:24And then kind of a hint, based on a hint

01:27that maybe it was male-dominated sexual selection.

01:30And that's what you are seeing here.

01:32And then-

01:33These air sacs, we gotta talk about these air sacs.

01:35Yeah, let's talk about the air sacs.

01:36What do you think about that?

01:37Well, the air sacs are kind of hard to miss.

01:41I have to tell you that there is zero evidence

01:43that Dreadnoughtus had air sacs.

01:46These are pneumatic gular pouches

01:49like a grouse would have today.

01:51Is it impossible?

01:53No, it's not impossible,

01:55but we don't have any evidence that we've had that.

01:58Now, I was told by the consultant on the show

02:02that they wanted to find a way to illustrate the fact

02:07that extinct animals must have had

02:09amazing soft tissue structures

02:12that will never be preserved in the fossil record,

02:14which is certainly true.

02:15If we only knew elephants from their skeletons,

02:18I probably wouldn't really know what an elephant looked like.

02:22So this is an example of a hypothetical feature

02:26that maybe we're missing completely in the fossil record

02:29that could have existed.

02:31Did they specifically have this?

02:33Probably not.

02:34Is it impossible that they had this?

02:36No, it's also not,

02:38but we don't have any evidence of it.

02:40What we do have though,

02:41is we have their cervical vertebrae,

02:43cervical vertebrae.

02:45And the cervical vertebrae are very pneumatic,

02:48meaning that they have a system of air tubes

02:52and air bladders that invade the bone

02:55over the lifetime of the animal.

02:56So the bone becomes more honeycombed with air over time,

03:00making it very light,

03:01but still retaining most of the strength.

03:03Because if you have a 40 foot long neck,

03:06a 40 foot long lever,

03:07you don't wanna put a lot of weight

03:09at the end of that lever.

03:10So they have these very lightly built pneumatic necks,

03:14which I guess gave them the idea,

03:15okay, there's air in the neck,

03:17there's a lot of air in the neck.

03:19Why not something like male grouses in the breeding season

03:23that have these pneumatic cooler pouches

03:25that pop out like that?

03:27Thinking of a story of Dreadnoughtus.

03:31I know, it's always interesting to draw inspiration

03:34from modern creatures.

03:36There he goes.

03:37But I guess we'll have to hold out

03:39for any more fossil or soft tissue preservation.

03:43Yeah, there's certain things

03:44that we're just never going to know,

03:46and we kind of have to live with that disappointment.

03:50But there are a lot of soft tissue features

03:52that extinct creatures have

03:53that we're just never going to find.

03:56We can make inferences about them.

03:57Sometimes we can do that from molecular work

04:01with modern creatures.

04:02We can look at the DNA from groups of related creatures

04:06and kind of figure out where that trait must have started.

04:10Occasionally you get soft tissue structures preserved

04:15if you have very clay deposits

04:19that can preserve that kind of resolution,

04:21but that's very rare.

04:21And I don't see that scenario happening

04:23for big things like sauropods.

04:25That happens for little things like birds.

04:28And then there's always the promise

04:30of molecular paleontology,

04:31where we routinely cover now,

04:34recover blood vessels and blood cells

04:37and proteins from dinosaurs and other extinct creatures.

04:41A few DNA bases have been recovered.

04:43Is it possible we'll have

04:45a genome of a dinosaur,

04:46an Atlanavian dinosaur in the future?

04:50I don't know.

04:50It's a pretty high mountain to climb,

04:52but I can't say that it's impossible.

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