Top 5 Cool Fossil Animal Posts of 2017

Ok friends. I posted a lot in 2017 (37 times!) so in trying to narrow down the top posts this year, I thought about narrowing it down to just dinosaurs, but that didn’t seem fair. So, in order of appearance, here are the top 5 cool fossil animals posts of 2017:


February 2017: [Bulbasaurus] a small-sized adult dicynodont from the Permian, which was named for its bulbous nose.

Bulbasaurus by M. Celesky

May 2017: [Zuul] the most complete North American ankylosaur ever found. Its head is covered in horns, giving it the appearance of Zuul, from Ghostbusters.

Zuul and Zuul. Left by D. Dufault.

July 2017: [Coronodon] a whale from the Oligocene whose teeth had many bumps for filter feeding.

Coronodon by A. Gennari.

September 2017: And speaking of filter feeding – [Morturneria] a plesiosaur from Antarctica with a ton of tiny teeth that it used as a sieve.

Morturneria by S.J.G.

December 2017: The trove of [pterosaur eggs], some with embryos, from the Early Cretaceous that tell us a lot about the growth of pterosaur babies and the nesting habits of the adults.

The pterosaur eggs.

Honorable mention: The ongoing dinosaur tree debate [1] [2], which isn’t a cool fossil animal, but could completely change how we think about (the coolest) fossil animals.

Note #1: between the holidays and traveling to a conference, I will not be back for a while. But fear not, DrNeurosaurus will return in February 2018.

Note #2: Our book SHE FOUND FOSSILS is available! Check here for details: She Found Fossils

Pterosaur Eggs and Nests

Last week, a [paper] was published that described an amazing fossil find. In China, in sediments dating to the Early Cretaceous, the authors found over 200 pterosaur eggs! Remember, pterosaurs are flying reptiles that lived alongside the dinosaurs, but are not dinosaurs themselves. Based on an adult specimen found with the eggs, the authors identified the fossils as Hamipterus tianshanensis.

A reconstruction of Hamipterus by C. Zhao.

These pterosaur eggs are preserved in 3 dimensions, which is a rare thing on its own. The authors used CT scanning and very careful preparation to look inside many of the eggs. Out of the 200-ish eggs, 16 of them had parts of embryos. The rest were filled with sediment, which potentially helped them stay in 3 dimensions as they became fossils.

Figure 2A from the paper showing the eggs and some adult bones.

The embryos all showed different levels of development, meaning that they were different ages (and that they were laid at different times). This tells us that many adult pterosaurs were nesting together and laying their eggs around the same time. The embryos also showed that their legs were more developed than their arms, even in embryos that were close to hatching. This tells us that these baby pterosaurs could not fly when they first hatched, but they could probably walk around. Because they couldn’t fly, their parents probably had to take care of them until they learned how to fly.

The authors think a storm came through while the pterosaurs were nesting and washed the eggs and some adults into a nearby lake. There might be more eggs under the first layer, so there might be more to find out from this wonderful find.

A Sauropod Footprint with a Skin Impression

This week, a new [paper] was published that described the largest sauropod footprint ever found from the Early Cretaceous (146-100 millions of years ago) of Korea. The footprint is more than 50cm (20 inches) in diameter!

The authors found something very rare inside the footprint: a dinosaur skin impression. That’s the equivalent of leaving a palm print on wet cement, like on the Hollywood Walk of Fame.

Mickey Mouse’s hand and footprints on the Hollywood Walk of Fame. From Pinterest.

The impression preserves interlocked hexagons that have a range of sizes. They seem to get smaller on the outsides of the impression.

Figure 2A from the paper showing the footprint on the left and a close up of the skin impression on the right.

The authors analyzed the sediment around the footprint to try and understand why skin impressions are so rare. They found that these impressions were left in on a muddy surface that had dried enough to preserve the impression. That muddy surface had to stay dry afterwards, and not get covered over by water. If more flooding had occurred, the print would have disappeared. The muddy surface also had to be covered by a thin layer of bacteria in order to hold the mud together. The combination of these conditions allowed the footprint and skin impression to stay preserved. These conditions can be hard to find in the same place and time, meaning that more dinosaur skin impressions could still be rare in the future.

The Giant Extinct Otter and its Giant Bite

Last week, an [article] was published that talked about the biting ability of the extinct giant otter, Siamogale melilutra. The [discovery] of this otter in south-western China was published in January of this year. It lived during the Miocene (23-5.3 million years ago). Siamogale weighed about 50 kg (110 pounds) and is the largest otter to have been found.

A reconstruction of Siamogale by M. Antón.

Living otters have a range of sizes from 4 kg (9 pounds) to 45 kg (100 pounds). They live all over the world in fresh and marine waters. And they’re really cute.

Otters holding hands. From Wikipedia.

This new paper compared the jaw mechanics of all of the living otters. Jaw mechanics include things like how much force the jaw can handle, muscle volumes, jaw stiffness, and how efficient the jaw is when biting. The authors used the jaw mechanics information from the living species to calculate the mechanics of Siamogale. Then the authors made CT scans of all of the skulls and tested the mechanics using computer software.

Figure 4 from the paper showing the computer models for the Giant River Otter and Siamogale. Red areas have higher stress, blue areas have less stress.

They found that Siamogale had a jaw 6 times stiffer than any of the living otters! This means that Siamogale had a super powerful bite. It probably used this powerful bite to eat foods like clams that have to be cracked open to enjoy. Some of the living otters use tools to help them crack the shells. Other living otters use their powerful bite. Siamogale’s super powerful bite probably let them eat foods that other animals at the time couldn’t eat.

The Dinosaur Tree Debate Continues

This week, a [reply] to the new [dinosaur tree] from March was published. You might recall that the March paper found a new set of relationships for dinosaurs. Ornithischians and theropods were found as closest relatives, forming the group Ornithoscelida, and sauropods and a group of early dinosaurs formed another group.

Evolutionary tree of dinosaurs published in March. Made by me.

The reply paper itself is only 1 page long. The authors looked at all of the characters used in the March analysis and rewrote them based on their own examination of the fossils. They also added a few more dinosaurs that were in important places in the tree.

Evolutionary tree of dinosaurs given by this new analysis. Made by me.

The authors ran their updated characters in a new evolutionary relationship analysis. The analysis gave them the standard evolutionary tree for dinosaurs. Theropods and sauropods are closest relatives, forming the saurischians, and ornithiscians are their own group.

You might think – ok, problem solved! But in fact, the authors ran a statistical analysis on their tree to see how many changes would need to be made to find the March tree. This analysis shows that only a few would have to be made to get from their tree to the March tree. This means that the trees are not very different, statistically speaking.

Another possibility. Made by me.

The authors also found that another tree is almost equally possible – one where sauropods and ornithischians are closest relatives and the theropods are their own group! WOW! What we know for sure is that early dinosaurs from each group looked very alike and so working out how they are all related to each other is going to take more research.

A New Look for Sinosauropteryx

Last week, a [paper] came out discussing the color patterns on the theropod dinosaur Sinosauropteryx. This dinosaur was a small-bodied meat eating dinosaur from the Cretaceous (133-120 million years ago) of China.

Figure 1 from the paper showing one of the specimens of Sinosauropteryx.

The authors took photos of 2 specimens of Sinosauropteryx under special lighting conditions. This helped them see the feathers that surround the skeletons. Feathers that had color in them are preserved more easily than feathers without color. So looking at the fossils helps us understand how colors were distributed on the animal. Artists then made reconstructions to show how the colors appeared on the dinosaur. They found that Sinosauropteryx had a striped tail, a bandit mask around its eyes, and a brown back with a white belly.

Figure 2A from the paper showing the color reconstruction on Sinosauropteryx.

The authors also wanted to test what the colors could tell us about what kind of habitat Sinosauropteryx lived in. Animals that live in open habitats (like deserts or grasslands) usually have darker colors on their back and lighter colors on their bellies. This helps break up their body shape so that predators have a harder time seeing them. Animals that live in closed habitats (like forests) usually are darker everywhere and have fewer areas with lighter colors. Think of the color differences between an antelope that lives in the grasslands, and an okapi that lives in the rainforest.

An antelope on the left showing coloration for open habitats. An okapi on the right showing coloration for closed habitats. Okapi from here.

To do this, the authors 3D printed models of the dinosaur and photographed it twice: once when it was fully sunny and once when it was completely cloudy. The full sun imitates the open habitat and the cloudy day imitates the closed habitat. They found that the shadows cast on the model on the sunny day match the color distribution found on the fossils. This means that Sinosauropteryx lived in open habitats.

Figure 2B from the paper showing how the open habitat where Sinosauropteryx lived and its coloration.

It probably used its bandit mask to reduce the sunlight entering its eyes. The striped tail, dark color on its back and light color on its belly helped camouflage it in open habitats, making it harder for predators to see it, and making it harder for prey to see it coming. This study shows us how new techniques can help us answer questions about how dinosaurs lived.

A Group of Reptiles Gets a New Head

This week, a [paper] came out describing a new fossil skull. The skull belongs to a reptile group called Drepanosaurs (dre-PAN-o-saurs). This group is well-known as we have several fossils of the bodies. Heads, however, have been harder to find.

A few different drepanosaurs. From here.

These reptiles evolved during the Permian (sometime around 260 million years ago), but did not become a diverse group until the Late Triassic (around 219 million years ago). That means they survived the biggest extinction event this planet has experienced – the Permo-Triassic Extinction Event. This occurred at 250 million years ago and around 90% of all life went extinct.

An approximation of what Earth looked like during the Permo-Triassic Extinction. (Just kidding – it’s Mordor).

The drepanosaurs lived on, though! These little reptiles looked very much like chameleons, but had some unique traits. The new fossil is called Avicranium renestoi (“avi” for bird, “cranium” for head, and “renesto” in honor of a paleontologist who works on this group).

Figure 2 from the paper showing the reconstruction of the skull bones. The long dotted line is the missing portion of the snout. The nose is to the left.

As its name suggests, the skull shows a mix of shapes, some looking very bird-like, and some looking very reptile-like. Let’s start with the bird-like features. The skull has is edentulous (has no teeth). Also, the part of the skull slightly back from the eyes is very domed. This leads to a bird-like braincase and [endocast]. These shapes are very similar to what we find in pterosaurs, modern birds, and some maniraptorans. Some of the features, like the back of the braincase and the ear, are very similar to other early reptiles. So Avicranium has a mix of bird-like and reptile-like features making up its skull.

An analysis of evolutionary relationships puts this group at the very base of the reptile tree. This shows us that some of these ‘bird traits’ evolved way earlier and in unrelated groups. It also shows us that the diversity in body shapes was much higher in the Triassic than we previously thought.

Baby Food for Ichthyosaurs

Last week, an [article] was published describing an old specimen that was hidden away in a museum collection at the University of Birmingham, United Kingdom. This specimen was of a baby ichthyosaur, only 70 cm long.

Some different ichthyosaurs. From here.

Ichthyosaurs were marine reptiles that lived during the Mesozoic Era. They had torpedo-shaped bodies, similar to modern dolphins and great white sharks. They came in all sorts of sizes and shapes!

Figure 1 from the paper showing the ichthyosaur fossil.

The authors know the specimen is a baby because some of its bones are still being developed and because of the proportions of the eyes and different bones in the skull. It was not found near an adult, so it wasn’t an embryo. This is the smallest specimen of Ichthyosaurus communis ever found!

Figure 9b from the article showing the hooklets in the stomach (by the black arrows). The long grey bones are ribs.

The interesting thing, though, is what they found in the stomach. Inside the ribs, the authors found several cephalopod hooklets. Remember, cephalopods are animals like octopus, squid, and nautilis. These hooklets are found on the underside of their tentacles, exactly where you’d find the suckers on an octopus arm.

A comparison of suckers and hooks on two different cephalopods. From here and here.

This indicates that the baby ichthyosaur was eating squid as its preferred food! Other species of ichthyosaur ate mostly fish as babies and transitioned to eating cephalopods as adults. This baby specimen shows that Ichthyosaurus communis ate cephalopods as babies, giving us a more thorough view of the diets of ichthyosaurs through their lifetimes.

Crab-Eating Hadrosaurs

Last week, a [paper] was published that described some fossil poops. That’s right, poops! When a poop fossilizes, it’s called a coprolite (‘copro’ for poop and ‘lite’ for stone).

A coprolite. From Wikipedia.

These coprolites came from Grand Staircase-Escalante National Monument in Utah and they date back to around 76-74 million years ago. The coprolites contain decayed wood bits that had been chewed up before swallowing. Of the dinosaurs known from this area and time, it is most likely that hadrosaurs were responsible for creating the poops. Hadrosaurs have specialized teeth that are really good at crushing and breaking tough vegetation to make it easier to digest. Instead of having a single row of teeth, hadrosaurs unite dozens of teeth into a thick collection of teeth (called a dental battery). All of the teeth work together to create a large, flat surface for grinding.

A dental battery with one tooth outlined in white. At the top of the battery, there is a flat surface for grinding. Photo by V. Williams.

The hadrosaur coprolites had more than just plants and decayed wood, though. They also contained bits of crab shell! And it wasn’t only 1 coprolite that had crab shell in it. Several different coprolites from different areas and different times had crab shell in them. This means that it wasn’t an accidental swallowing of a crab, but rather, that the hadrosaurs were eating them on purpose.

Figure 2b from the article showing the coprolite.

How can we be so sure though? We know how wide a hadrosaur mouth was and we know how big the crabs were. It turns out, the crabs would have taken up a large portion (20-60%) of the hadrosaur’s mouth! If the dinosaur didn’t want to eat the crab, it would have noticed it and spit it out. The authors think that during times where plant matter was harder to find, these dinosaurs would eat the decaying logs that crabs also ate. As the dinosaurs munched away on the wood, they’d eat the crabs as well, providing a good source of protein.

My own reconstruction of a hadrosaur, Maiasaura finding a crab. Drawing found on Pinterest. Log photo by C. Perrin. Crab photo by The Daily Dot.

This study shows us that even though we think teeth are specialized for one type of food, animals might eat a larger variety of items that we thought.

Cretaceous Hell Ants

At the beginning of September, a [paper] was published that described a new species of ant. Not just any ant! A hell ant from the Cretaceous. That was preserved in amber from Burma.

A photo of the hell ant in amber. The authors called the new species Linguamyrmex vladi.

This group of ants is extinct and known only from the Cretaceous (specifically around 98 million years ago). The amber is see-through, so the authors took high-resolution images of the ant through the amber. They also CT scanned it.

Figure 3 from the paper showing a reconstruction of the ant.

They found that this ant had a large horn coming off the head and a scythe-like jaw. A scythe is a curved metal tool for cutting tall grasses. It’s also what Death carries around.

Death, holding its scythe. From here.

These jaws were used to pin and pierce soft larvae, but could not be used to chew their prey. Instead, the authors think that after piercing the prey, the jaws would funnel blood down into the bend of the jaw, and then small hairs and suction would direct the blood into the ant’s mouth. This ant sucked blood like a vampire!

Figure 4 from the paper showing the hell ant and its prey.

Lastly, the CT analysis showed that the jaws are denser than the rest of the head. This analysis also showed that the increased density was due to metals in the jaw. These ants absorbed metals from their environment and used them to make their jaws stronger. It’s too bad that this group is extinct – it would have made for a killer nature show!