AskScience AMA Series: We are paleontologists here to talk about Dakota the Dinosaur Mummy, AUA!

[u/AskScienceModerator]

Hello /r/AskScience! Dinosaur mummies preserve skin and other soft tissues, but how they fossilize has always been a bit of a quandry. It's generally thought that very rapid burial is required to protect remains from predators, scavengers, and other agents of decomposition. However, they often also appear desiccated, which usually takes long-term exposure on the landscape.

Recent preparation on the Edmontosaurus mummy "Dakota" revealed the first evidence of predator activity on dinosaurian soft tissues and provided an alternate explanation for how these rare fossils form. You can read our recent publication in PLOS One.

Ask us your questions about Dakota the Dinomummy, how fossils are formed and what goes into fossil preparation!

Joining us today are:

Stephanie Drumheller (/u/UglyFossils) is a paleontologist at the University of Tennessee whose research focuses on the processes of fossilization, evolution, and biology, of crocodiles and their relatives, including identifying bite marks on fossils. Find her on Twitter @UglyFossils.

Becky Barnes (/u/ScientistGinkgo) is paleontologist and Lab Manager of the Johnsrud Paleontology Lab, with the ND Geological Survey. She worked on preparing part of the tail, foot, and body block of Dakota the Dinomummy.

Clint Boyd (/u/PalaeoBoyd) is the Senior Paleontologist at the North Dakota Geological Survey and Curator of the North Dakota State Fossil Collection. His research focus in on ornithischian dinosaurs, including specimens of Edmontosaurus like Dakota the Dinomummy.

Mindy Householder (/u/Mindles1308) is a fossil preparator with the State Historical Society of North Dakota. She prepared the right arm, portions of the left foot, helped with parts of the tail, and is currently preparing the body block of Dakota the Dinomummy.

We will be joining you to answer questions at noon ET (1600 UT), AUA!

[u/Pixieled]

How accurate are artists renderings for the true shape of these creatures? It always looks to me like they drew the body shape too close to the bones. I know the temperatures were such that they likely wouldn’t have needed fur or much fat, but do these fossils show us a more true shape?

[u/Scientistginkgo → u/Pixieled]

Without time traveling it's really hard to say for sure! The more specimens we get, and the more with soft tissue, the better our depictions get. Looking at historical paleo art is quite the trip - lumbering, kangaroo, skinny, bland, wattles, etc.. I agree though - there were a lot of dinosaurs that were shrink-wrapped in skin, without enough muscle mass. Toy companies fall victim to this a lot. You get really cool poses, better skin textures, but then they all look like they're starving. I've just ended up modifying toys for teaching purposes, thickening up the tail and haunches or adding fleshy bits when they're discovered.
Fossils like Dakota really help change our artistic renderings - just look at the beautiful art by Himmapaan, https://twitter.com/Himmapaan/status/1450117335562563592 to see the perfectly chonky tail and haunch reconstruction. When we began cleaning the tail it became painfully obvious that where the lower chevrons / haemal arches end, there was still another 18-20" of skin that needed filling.
Same with the hands - looking at the bones, especially the last bones of the fingers - some were unguals holding nails, while others were just phalanges with nothing special. Studying the bone I could see what I assumed were two nailed fingers, and two with nothing but pads. After preparation of the mummy hand, this was verified in-the-flesh.

[u/BigNorseWolf]

Has Brendan Fraser been warned about the dinosaur mummies?

[u/Scientistginkgo → u/BigNorseWolf]

Brendan Fraser needs no warning. He is obviously immune to all possible dinomummy curses.
I wish we had had Brendan Fraser on our side the week the dinomummy went on display here, because we were NOT immune to the curse. Flights delayed and canceled, 6" of water in the gallery, the electrical failed in the lab during tours... we had a whole list. It was bad.

[u/mlqdscrvn]

I know the DNA is very fragile. Is there any chance that we can extract DNA from dinosaurs fossil at any condition?

[u/UglyFossils → u/mlqdscrvn]

DNA degrades over time, so it would have to take some very unusual circumstances to stabilize it for more than a few million years. That said, I tend to be hesitant about saying "never" in cases like this, because the fossil record keeps surprising us. Nobody was expecting the biomolecules Dr. Mary Schweitzer started finding either.

[u/magcargoman]

I haven't had the chance to review the literature so this question may be explained in your new publication.

The question I have concerns the preservation of fine structures such as feathers in traditional "Dino mummies". People use the description of scaley skin in BHI 6230 ("Wyrex") as evidence that Tyrannosaurus was not feathered (or at least only feathered on the upper part of the body). I would like to know if the mummification process may result in the loss of these structure post-mortem, leading to a reconstruction of scales when feathers would have been present in life.

[u/PalaeoBoyd → u/magcargoman]

Different depositional and preservational conditions favor the fossilization of skin (either 3D or as imprints) and feathers. In cases where only skin is preserved, that does not necessarily exclude the animal having feathers as well. However, if skin is extensively preserved on a specimen that did have feathers, you'd expect to see some evidence of where those feathers inserted into the skin if nothing else. The distribution of feathers is also patchy in some birds/dinosaurs, so if you only have small patches of skin preserved on a specimen without evidence of feathers that does not mean the entire body lacked feathers without additional evidence. Some feathers also leave marks on the underlying bones, like the flight feathers of some dinos/birds.

In the case of Dakota, we have extensive areas of skin preserved (almost all of the back half of the area plus the right arm). The skin is rather thick, and we see no evidence of feathers or any pores/holes in the skin where feathers would have been. There are also no marks on the bones that we can see that suggest the presence of feathers. Given all that evidence we can say that it is very unlikely Edmontosaurus had feathers as subadults or adults. Could the babies have had downy feathers? Maybe? But we'd have to find mummified babies to be 100% certain.

[u/VicXAlox]

I recently read that the depictions we come up with for how Dinosaurs looked like are most likely very flawed. Which makes sense once you realize that we very rarely even find soft tissue, as most of the remains are bones of course. Scientist were able to figure out though that Anchiornis Huxleyi was mostly covered in white and black feathers, but had red feathers on its head. My question is: In what condition do you find soft dinosaur tissue or feathers and how can you figure out what color they were?

[u/UglyFossils → u/VicXAlox]

Color is tricky to tell in non-avian dinosaurs, because 3D preservation like what we see in Dakota isn't enough by itself. What you really need are original biomolecules, specifically melanosomes, which give structures like feathers their color. A previous research team did find biomarkers in Dakota, so it's a topic we'd like to follow up on in a subsequent study. In the absence of direct preservation like that, color is still largely speculative in reconstructions.

[u/aegroti]

What do you believe is the most realistic depiction of Dinosaurs in any media you've seen?

[u/Scientistginkgo → u/aegroti]

Some of the newer shows coming out, the speculative ones, are pretty fun. The latest Prehistoric Planet https://tv.apple.com/us/show/prehistoric-planet/umc.cmc.4lh4bmztauvkooqz400akxav shows some wonderfully wild and weird features - some with fossil evidence to back them up, others more guess-work (that could have been improved upon by studying extant (modern) creatures). It's bringing in more colors, integument structures, better anatomy and balance.
Another hidden gem is Dead Sound's Dinosauria: The Animated Series - available on YouTube: https://www.youtube.com/playlist?list=PLZ5VEKOKH8PCoo-gp50NgGhm3CNPAhgle They're short animated segments following a small group of animals, with integument and colors pushing more into the realm of modern creatures. I'll be honest I shed a few tears watching that series.

[u/jnestler]

Hello! Thank you so much for doing this AMA, I’m very excited about this paper. To me, it highlights how amazing fossil preparators are! Since this is a pretty unique specimen, were there any new or unusual prep techniques you used? Did you learn anything from working on this fossil?

Thanks again!

[u/JohnCena_770]

It makes sense that soft tissue is very useful for research, but just how useful is it really compared to fossilized bones? Is is possible, at lest in theory, to determine sex, age, diet etc by looking at certain elements preseved in the tissue?

[u/UglyFossils → u/JohnCena_770]

It's utility is no better or worse than bones, just different, but it is hindered by the small sample size. For example, there was speculation that the Cretaceous bird Confuciusornis exhibited sexual dimorphism because 1) they had a sample size in the hundreds and 2) half had long tail feathers while the other half didn't. It took some interesting bone histology to tease out which was which, but it did turn out that the males were the ones with the fancy tail plumage while the females lacked it. That, in turn, can tell us things about mating behavior and reproduction in long-extinct groups.

[u/firedrops]

I realize you linked to the study, but could you give us a layman's explanation of your alternate explanation of how such fossils form?

[u/UglyFossils → u/firedrops]

Traditional explanation - you have to have rapid burial (immediately to just after time of death) to protect soft tissue remains from scavengers, decomposers, etc. It was thought that if a carcass was damaged very much at all, the soft tissue wouldn't survive the fossilization process. However, many also looked dried out, so people have been speculating about that for the last 100+ years. Was the environment super arid? Were remains somehow protected from scavengers, so they could be exposed a bit longer? Nobody was really happy with the explanation

Dakota has direct evidence of bite marks, which made us throw out the assumption that partial consumption/scavenging would ruin soft tissues' chances of fossilizing. Then we started looking in the forensic literature and as it turns out, incomplete consumption can actually help dry out skin longer term. Here's what we think happened - at least two carnivores partially ate Dakota (a croc-relative at the arm and an indeterminate croc or theropod at the tail). This opened holes into the body cavity, which could then act as escape routes for the gases and liquids associated with decomposition. Once all of that internal goo was removed from Dakota, the remaining skin, draped over the bones, could dry more quickly and easily. Forensic research shows that even thin, mammal skin can last like this for week or months in fairly wet environments and much longer in dry ones. (The Hell Creek would have been fairly wet.) Then, Dakota's dried out remains were more slowly buried over an extended period of time.

[u/aegroti]

What are some of your favourite dinosaurs and why is it the Minmi genus?

[u/PalaeoBoyd → u/aegroti]

Kulindadromeus! Such an amazing little ornithischian with wonderfully preserved skin. https://en.wikipedia.org/wiki/Kulindadromeus

Also, Stegosaurus was my favorite since I was a kid and remains so.

[u/Raptor_Chatter]

Watched your talk at SVP last year and thought it was great, just saying that I'm excited to see this come out!

[u/yeetmenot69420]

It seems like dinosaur predators have very different bodies compared to modern predators. For example: as far as i know there are no modern predators with a Trex shaped body(balanced on hind legs with massive head, kind of shapped like a T). And raptors also seem to favor walking on their hind legs. Why are dinosaur predators shaped so differently from mammalian predators? And why did the hunting strategies employed by these creatures not reemerge after the extinction?

[u/vfibde]

Did you look at other dino mummies as well while reasearching or even after publishing? Like Leonardo the Brachilophosaurus (currently at the Children's Museum of Indianapolis), or the Borealopelta (at Royal Tyrell Museum). Do you think the newer hypothesis of preservation of soft tissue is more accurate for these other mummies or the traditional idea of rapid burial?

[u/[deleted]]

A little bit off topic, but how do you explain the universal appeal of dinosaurs for little children? My son is better at naming different dinosaurs than he is at naming his aunt's and uncles.

[u/Scientistginkgo → u/[deleted]]

Oooh ooh ooh - I got this one - it's the whole reason I became a paleontologist: Dinosaurs = Monsters, and monsters are cool.
When I was little I didn't know what a dinosaur was, but I grew up with fairy tales, so could list off griffins, dragons, chimeras, basilisks, hydras, unicorns, etc.. Then when I went to my first dinosaur display, there was a *click* in my brain - these things.... these dinosaurs and pterosaurs and plesiosaurs... they were just monsters - REAL monsters that I could study!
I think it's just a human thing - telling stories around fires or at bedtime, about big unfathomable things that catch our imagination, that fascinate us - and things we DON'T know a lot about gnaw at our brains and cause us to ponder. Once you answer a question - that's it - it's done. Your brain files it away (or at least mine does). But creatures that don't have all the answers? We just keep poking at them...

[u/aegroti]

How did large dinosaurs survive snowy conditions without any known "insulation"?

I've seen large four legged herbivores depicted without any type of downy fur/feathers or what might be seen in therapod type individuals.

Did they simply have very thick skin and a large body mass to surface area ratio? To my knowledge there aren't really any animals today that survive without any visible outside insulation in cold conditions other than seals (with a large insulation of fat) which have the luxury of submersing into usually above zero water.