Fossilized Vomit and Feces Are Delighting Paleontologists

The fossilized vomit.

The fossilized vomit.
Photo: Courtesy Caleb Gordon

How Can Fossils Tell Us About the P...
How Can Fossils Tell Us About the Past?

Fossil skeletons tell us a lot about extinct species; without them we would not be able to merge the old life. However, equally important are the fossils that may not immediately capture our imagination, awe us or even be recognizable to non-paleontologists. The traces an animal has made in its lifetime – footprints, tail resistances, nests, burrows, feces, and vomit – are all examples of ichno fossils. These may not attract museum audiences such as a T. rex skull yes, but they reveal behaviour and provide insightful clues in the old environment. That we can not only discover such things after millions of years, but also recognize them for what they are, is absolutely amazing.

Two articles published this month reveal exciting new ichnofossil discoveries. They describe two very different species from two different geological eras, but are nevertheless connected by one important detail: these fossils preserve digestive remains – vomit and poop – expelled by long-gone creatures.

Ichno fossils such as coprolites (fossilized stool) and fossilized stomach contents have been recognized since the early 1800s. Like any other enterprise, paleontology has evolved over the past 200 years since its inception. Our ability to recognize other types of ichno fossils has increased, and now scientists are able to detect fossil gastroliths (swallowed stones to help an animal with digestion), stomach pellets (like the kind of vomit material you might find from an owl) determine, consumulites (fossilized material from the digestive tract) and regurgitalites (fossil vomit). The list continues.

And while the popular press rightly continues to highlight the remarkable skeletal fossil finds, ichnofossil discoveries – despite their importance – are receiving significantly less attention.

In a paper Published in Scientific Reports, paleontologists report the first coprolites ever discovered at the La Brea Tar Pits in Los Angeles. Small, abundant and resembling modern rodent poop, these fossil droppings were initially considered the droppings of contemporary rats on museum grounds. However, after extensive study, it was determined that these are the 50,000-year-old remains of an ancient woodrat of the genus Neotoma. Research co-authors Laura Tewksbury and Karin Rice discovered these coprolites.

“While the personnel working on the excavation and the initial bulk preparation of the material suspected early on that the material could be coprolites, more than a century [La Brea Tar Pits] had never reported such fossils to be preserved, “excavator Laura Tewksbury said in an email to Gizmodo. “Only when hundreds of them were found, from an area where such an abundance of contamination was simply not possible, did the hypothesis get a hold.”

So why is this important? Why is this nest of old woodrat poop an important discovery on a site known the world over for its wealth of impressive fossils, including huge Colombian mammoths, mastodons, terrible wolves, camels and saber-toothed cats.

First, these are the only known coprolites that have survived in what we call a tar pit, but are actually a natural asphalt seepage. We now know that this preservation is possible. This gives an incentive to paleontologists in other places around the world to look for similar ancient remains.

Second, these coprolites open a door to the ecosystem of that period. The survey indicates that old Neotoma at C3 plants, a term that denotes largely woody, grassy flora known to be present on the La Brea Tar Pits site.

Example coprolites (A) before asphalt removal with surrounding sediments, (B) intact pellets with vegetable material, (C) isolated, cleaned pellets.

Example coprolites (A) before asphalt removal with surrounding sediments, (B) intact pellets with vegetable material, (C) isolated, cleaned pellets.
Statue: Mychajliw et al. 2020 (Scientific reports)

But, as lead author and paleoecologist Alexis Mychajliw explained in an email to Gizmodo, ‘more importantly, the plant macro fossils in the nest represent a single point in time. So we captured a full community snapshot in the nest. ‘

“For years at Rancho La Brea it was as if all the actors (the megafauna) were present, but no stage to put them on (the plants and the surrounding ecosystem),” she said. “If you want to study something like a food chain, the most important step is that first rung on the ladder: the plants! And then comes the primary consumers, like herbivorous rodents. And that’s what this woodrat nest lets us do: see this interaction between the first and second steps of the food chain as captured in the fecal pellets. We have laid the groundwork for understanding the interactions of organisms higher up in the food chain, such as the iconic saber-toothed cats, and can better understand how climate change shapes entire ecosystems rather than specific species. We have paved the way. “

We go back more than 200 million years, separated Research published in the journal Palaios indicates that an enigmatic fossil discovered by Zachary Lavender in 2010 actually vomits from an ancient reptile. On loan to the Yale Peabody Museum of Natural History from Arizona’s Petrified Forest National Park, where it was found, the fossil was initially thought to be just bone. But fossil prep and co-author Brian Roach began to suspect that this wasn’t just a bone fossil while he was working on it.

Zachary Lavender prepares to excavate the specimen in 2010 in Arizona's Petrified Forest National Park.

Zachary Lavender prepares to excavate the specimen in 2010 in Arizona’s Petrified Forest National Park.
Photo: Caleb Gordon

“Fossil-making is a painstaking, time-consuming work,” he wrote in an email to Gizmodo, “and it makes you look at the specimen very carefully and think about it. I started to suspect that the specimen was a regurgitalite while I was preparing it because it was so unusual – the bones were compressed into separate clumps that looked like they couldn’t be the result of the environmental processes that usually sort bones and concentrate burial . “

But suspecting something is fossil vomiting and proving that they are two very different things. Unlike bone fossils that have a distinctive and more recognizable shape, things like fossil vomit, feces, or other digestive debris can take different shapes and sizes. Next, consider what processes it has gone through for millions of years from when it left the animal’s body: whether or not it was carried away by water to rest with other bones, how the fossil may have been influenced by pressure through so many geological time periods , and many other variables. There are so many options to think about when looking at an ichno fossil that the process of defining it itself is a study of great research.

Paleo-ecologist Karen Chin, who has conducted extensive research on coprolites, explained this in a telephone conversation with Gizmodo. “I understand the challenges Caleb Gordon and his co-authors faced when you got this weird copy and said,” Okay, the first question I have to answer is, what is it? “I have studied a lot of coprolites and always have to carefully describe the evidence that they are coprolites, even if I am pretty sure they are fossil feces! “

The authors determined that the jumbled mass of bones was Revueltosaurus, a pseudosuchian archosaurus from the late Triassic, based on the teeth and osteoderms.

“The bones in the specimen are bundled and aligned in a way that suggests they were packaged in the digestive tract,” wrote PhD student and lead author Caleb Gordon in an email to Gizmodo. Other abiotic factors (such as river movement) can also pack bones together, but they tend to sort bones by size or shape, and the bones are packed together in [this specimen] are a range of shapes and sizes. This suggests that the bones are clustered by biotic processes. ‘

Artist's depiction of the being who left the regurgitalite.

Artist’s depiction of the being that the regurgitalite left behind.
Illustration: Brian Roach (Palaios)

At some point in a digestive tract, perhaps, but because a carnivore’s skeletal fossils were not found nearby, they concluded that it couldn’t just be fossil material from within a digestive tract. This meant that the copy was a coprolite or a regurgitalite. But how do you determine which?

The large size of Revueltosaurus bones indicate large bites of a significant animal, such as a phytosaurus, a temnospondyl or a rauisuchid, predatory species known from that area and time period. If ancient species follow their existing counterparts, the bones in this specimen may indicate fossil vomit – surrendering those parts of the food it cannot digest.

Many animals use a special behavior called routine vomiting to remove indigestible or unwanted parts of their meals, such as bones or fur … [This includes] birds, crocodiles, lizards – even some fish and sea lions! Based on where these living animals are located on a phylogenetic tree, we could predict that many extinct groups, such as the ancestors of modern crocodiles, also produced stomach pellets, “said Gordon.

Other indications that the specimen were not feces: it did not fit in a known form of a coprolite; Carnivore coprolites are known to be high in phosphate, while this one is low in phosphate; the bones in this specimen showed no sign of heartburn; and muscle tissue survived, indicating that it has not completely passed through an animal’s digestive system.

‘[W]e found phosphated muscle fibers under the scanning electron microscope. This thing is over 200 million years old and the preservation was incredible – you could see the remains of myofibrils. It was like a little window on the physiology of this[[[[Revueltosaurus]Gordon wrote.

You can almost hear Gordon’s excitement through his email, “This specimen and the Chinle formation [from which it came] In general, give us a snapshot of a time when theropod dinosaurs hid in the shadow of pseudosuchians, and the galloping crocodile ancestors ruled the world. ‘

Mychajliw and colleagues infused their research with humor. Whether they refer to their project as “who pooped in that box !?” or explained that one of the most exciting aspects of this research was “being able to coat 50,000 year old rodent fecal pellets for science and now they are shimmering purple gems”, Mychajliw would like to remind people that science is fun and we can do important scientific research with a sense of humor. ”

Chin pondered, “I remember talking to Anthony Martin who suggested that trace fossils were the Rodney Dangerfields of paleontology. And within trace fossils I think coprolites are at the bottom anyway! I think there is still a natural bias from the public and some paleontologists think trace fossils are not very informative or important to contribute to our understanding of the past. But I think the bias is less pronounced these days, in the sense that there are many more people who now realize that we need to take a more balanced view of different fossils to understand ancient ecosystems. ”

But what about the average person reading this for the first time who might be thinking “GROSS”?

The aforementioned Anthony Martin, ichnologist and professor at Emory University, has written a number of popular books on ichno fossils. He told Gizmodo, “It’s understandable that some people consider vomiting or feces to be ‘gross’ because we associate those features in people with bad faces, sounds and smells. But every animal needs to eat, so puking and defecating has been part of everyday life for more than 500 million years, from ocean depths to mountain peaks and from pole to pole. So once we suppress our disgust and marvel, we can learn so much about what animals ate from long ago. ‘

“I hope the average person realizes that these kinds of trace fossils – no matter how distasteful they seem – give us important snapshots of what animals ate thousands or millions of years ago,” said Martin. “Instead of thinking,” Ew, disgusting, consider these more like these animals sending you “meal selfies” from the past! “

Jeanne Timmons (@beautiful sentences) is a freelance writer from New Hampshire who blogs on paleontology and archeology mainly


1 thought on “Fossilized Vomit and Feces Are Delighting Paleontologists”

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