The secret before the shit! This time we opened a box of 38 million-year-old poops

The Earth has existed for 4.6 billion years, and the life explosion occurred 500 million years ago. During this long period of time, the excrement of creatures was constantly being born in the land, oceans, rivers, and mountains throughout the Phanerozoic Eon. Most of the excrement decomposed and disappeared, and some was eaten, but a very small amount of excrement was fortunately preserved as fossils, becoming "precious" evidence for our understanding of the living conditions of extinct creatures.

The study of coprolite has spanned two centuries. Two hundred years ago, in 1829, British paleontologist William Buckland coined the term "coprolite", which later became the general term for all coprolite.

The information provided by coprolites makes up for the shortcomings of skeletal fossils and becomes an indispensable mirror in paleontological research, reflecting feeding characteristics, digestive tract structure, paleoenvironment and food chain relationships, etc.

Quick Facts

Unlike the dinosaur skeletons we often see in museums, coprolites are trace fossils rather than physical fossils. Trace fossils refer to various traces left by organisms during their lives, such as footprints, crawling marks, gastric stones, bite marks, etc.

The earliest known ichthyosaur coprolites, containing undigested scales, teeth and bones (Credit: William Buckland, 1829)

Recently, a paper on the study of canine feces fossils from Yuanmou area in Yunnan Province millions of years ago has been published. Let’s take a look at how the information in the feces fossils is interpreted.

Part 1

Finding the "owner" of feces

The picture below shows 38 coprolites found by researchers. Do they look like the balls we hit with slingshots when we were kids?

The primary purpose of coprolite research is to find the "owner" of the feces. How to start?

First, we look at shape and color.

These feces are round or oblong, with one end larger and the other smaller, and the length ranges from 1.5 cm to 5.5 cm. If you break open the feces, the inside is white, and the outside is yellow, brown, and black, which indicates that fresh feces may be white, and the different colors on the surface are the colors of mineralization during the burial process.

Secondly, micro-CT scanning and X-ray energy spectrum analysis.

The calcium content in the feces was found to be very high, which is why the feces balls are so hard. We also found bone fragments of small animals in the feces, including a small shoulder blade! Obviously, the feces belonged to carnivores, especially animals that eat bones, so they must be dogs, hyenas, tigers, etc.

Finally, identify the "suspect" who is defecating based on body size.

The carnivores of the Yuanmou fauna millions of years ago were arranged one by one, and the size of the feces was inferred based on the size of the feces. The final target fell on a canine animal - the Yuanmou pseudojackal. Jackals are smaller than hyenas and larger than puppies, making them the most suitable "suspects". As a result, the study established a new genus and species of coprolites, Cuocopros yuanmouensis, which roughly means "Yuanmou dog feces". In addition, the researchers also reconstructed the climate background of the Yuanmou Basin, which was earlier than the Yuanmou Man, through multidisciplinary analysis such as morphology, palynology and lithostratigraphy, and explored the food chain relationship between animals, Yuanmou Man and plants.

Part 2

Yuanmou Man Homeland

The age of Yuanmou Pseudojackal coprolites is a little earlier than that of Yuanmou Man , who lived 1.7 million years ago. At that time, in addition to ancient humans, there were also Yuanmou wolves, Yunnan horses, Chinese rhinos, deer, tigers and other animals. What kind of environment did these ancient creatures live in, and what did their homes look like a million years ago? Based on the pollen, we can infer the ecological environment at that time. Are there plant pollen in the feces of carnivores? Yes, but there are great differences in the pollen concentration in their feces. Eating the intestines of herbivores has a great impact on the pollen combination in the feces. So the researchers took samples from the strata where the coprolites were buried. The pollen concentration in the strata can more accurately reflect the vegetation combination in the environment at that time.

As a result, 13 types of plants were found in the strata, of which 48% were trees, including pine trees, walnuts, etc., and 48% were herbaceous plants and shrubs, such as roses, gentians, and Asteraceae, and the rest were ferns. These pollen evidences show that Yuanmou a million years ago was a vegetation environment where subtropical evergreen broad-leaved forests and drought-resistant herbaceous shrubs coexisted. The climate was warm and often dry, and it was speculated to be in the dry and hot valley type stage. People generally believe that river valleys are the places with the least water shortage. In fact, some river valleys are dry and rainless, and the vegetation is desolate. This kind of river valley is called a "dry and hot valley" and is mostly distributed in tropical or subtropical regions. In such a dry and hot environment, a group of jackals were foraging on the mudflats by the river, and their feces fell inadvertently. The weather was hot, the water evaporated quickly, and the dry feces were buried underground by mud and sand.

Part 3

Who ate whom?

There are many members of the Yuanmou Fauna, and they live in the same habitat. There are carnivorous tigers, leopards, and jackals, plant-eating saber-toothed elephants, deer, rhinos, Yunnan horses, and omnivorous ancient humans. These species naturally depict a scene of survival competition between predators and prey, in which each organism occupies its own ecological niche and plays its own role. From the coprolites, we can directly see examples of predators and prey, and from the results of spore analysis, we can see the instability of the climate at that time.

The dry and changing environment caused herbivorous animals to migrate and large carnivores to evacuate, which had an important impact on the migration and evolution of mammals and ancient humans. From a small piece of feces, we can get a glimpse into the complex food chain. At the end of the paper, the researchers reconstructed the ancient environment in their minds millions of years ago: in a dry and rainless river valley, a grassland formed around a small pond. Herbivorous animals such as Chinese rhinoceros, Yunnan horses, and deer foraged for food while being vigilant (not to become food), while carnivorous animals such as tigers, hyenas, and jackals were looking for opportunities not far away, and the ancestors of ancient humans were ready to hunt at any time with simple tools in their hands. Scientists hope that by revealing the relationship between different species in the same ancient ecological environment, it will cause people to think about the struggle for survival between climate, vegetation, fauna, and ancient humans.

Source: Science Institute