Where in the World is DrNeurosaurus?

Hello friends. It’s been a while since I posted. I have not forgotten about you! I’m about 2 weeks away from meeting the tiny human I’ve been growing and have been running pretty low on energy. You may or may not know that the team involved in running DrNeurosaurus is just me. That means I don’t have any backup author to write posts when I can’t, and my recent life changes have made that more frequent than I would like.

Even though I’ve wanted to write posts each of these past weeks, I have not been able to. I will be returning to regular posting, but I need a few months off first. I will be starting a new job and caring for a new family member, and don’t anticipate much free time in the coming months. When I do return (hopefully in the early Fall), I will try to post at least once a month. As things normalize, I will hopefully be able to return to more frequent posting. See you soon!

A Giant Ichthyosaur from the United Kingdom

Last week, an [article] came out about an ichthyosaur from the United Kingdom. Ichthyosaurs are marine reptiles the lived during the Mesozoic. They had bodies shaped like dolphins and gave birth to their babies instead of laying eggs.

An ichthyosaur. From here.

This article described a few new specimens that were found in the United Kingdom. The specimens are pieces of the lower jaw bone, from slightly different time periods, but all from the Triassic (251-199 million years ago). Now, usually isolated pieces of bone do not make the news, but these lower jaw pieces are HUGE.

Figure 5A from the paper showing one of the jaw pieces.

The authors compared the pieces to other ichthyosaurs of the time and place and found that in one case, the animal could have measured 20-25 meters long. That’s almost the size of a blue whale! In the case of the other specimen, it might have been even larger.

A drawing of Shonisaurus, a related ichthyosaur. By N. Tamura.

Even though large mammals are found in our oceans today, during the Triassic, there was a broad diversity of reptiles ruling the seas.

The Short-Faced Reptile from Connecticut

Last week, a new little reptile was [described] from the Late Triassic (around 212 million years ago) of Connecticut (USA). The specimen was originally found in 1965, but it took almost 30 years before its first description was published in 1993. This new study adds in modern scanning and analysis techniques to get a better idea of what this animal was and how it lived.

A couple of rhynchosaurians with human legs for scale. From Pinterest.

The reptile is a rhyncosaurian, a type of reptile distantly related to crocodiles, dinosaurs, and birds. Rhyncosaurians lived only during the Triassic and were typically small, but some could grow up to 2 meters long. This new rhynchosaur is named Colobops novaportensis, meaning ‘short-faced’ and ‘from New Haven,’ the area where is was discovered. Colobops is interesting because of its small size and because of a few features of its head.

Figure 1A of the paper showing the top of the skull. The front of the skull is pointing up. This image was made using CT scans.

To start, the part of the face in front of the eyes, called the rostrum, is very short. It’s only about a quarter of the length of the skull! That’s very small for a reptile. Its whole skull is only 2.5 cm (1 inch) long. So, this is a very small rhynchosaurian. Secondly, the skull has features that indicate very large muscles for biting. Even though the muscles themselves do not fossilize, the space those muscles occupy and their bony attachment points do fossilize. These bones can give us an estimate of how large the muscles were. Altogether, this species is very small and its bite was much stronger than expected for its size.

An artist reconstruction of Colobops. By M. Hanson.

This study shows that we can always learn more about animals by using up-to-date techniques that were not always available. It also shows how science can occur in a series of steps that build on each other.

An Ammonite in Oregon

Today we’re focusing on a little story out of Bend, Oregon. A 6-year-old girl named Naomi Vaughan went off to play in the sagebrush as her mom cheered on a JV soccer team, and she found something extraordinary.

A map of the United States from Google, showing where Bend, Oregon is located.

Naomi decided to dig in the dirt, and in her explorations, she found a shiny, spiral-shaped fossil. The fossil was an ammonite! These extinct, marine animals are related to today’s squids, octopuses, and nautilis. They lived during the Paleozoic and Mesozoic (400-66 million years ago) and went extinct when the non-avian dinosaurs did at the end of the Mesozoic.

A picture of ammonites. Drawn by Ray Troll.

But how did Naomi’s ammonite make it to Bend? Ammonites aren’t known from Bend, but are common 80 miles away. Paleontologists think that her ammonite was brought in from another state, and maybe tossed away or lost in the field. One paleontologist narrowed down the age of the fossil to somewhere between 100 and 66 million years old.

Naomi Vaughan holding her fossil. Photo by Joe Kline/Bulletin photo.

One thing is for sure, Naomi is now the proud discoverer of a new ammonite fossil.

A New Baby Bird

This week, a [paper] came out describing a new baby enantiornithine. Enantiornithines are early birds that are closely related to the birds we see today, but part of a separate group. All enantiornithines went extinct at the end of the Cretaceous.

An enantiornithine. By S. Abramowicz.

This paper describes a fossil from the Early Cretaceous of Spain that preserves most of the skeleton. It is a remarkable specimen because it died around the time of birth. Because of its young age, it can give us a special glimpse of how the skeletons of enantiornithines developed in their lives.

Figure 1 from the paper showing the fossil. The head is up and the face is pointing to the right.

Of all the bones in this fossil, the sternum and the tail give us the most information into enantiornithine skeletons. The sternum is the large breastbone in birds that anchor the flight muscles. Enantiornithines also have a large sternum. This fossil shows that the sternum starts to ossify (or turn into bone) later than the other bones in the skeleton. It does this in a complicated pattern that is different from what we see in other enantiornithines and modern birds.

Figure 4g from the paper showing the ossification pattern of the sternum. It starts out as cartilage (grey) and it starts to ossify in the red, blue, and yellow sections. The bone grows out from there until the whole sternum is made of bone.

The tail in birds is usually fused into a bone called the pygostyle. In young birds, the vertebrae are still separate. This fossil has more separate vertebrae than the adult enantiornithines.

Figure 4 d and e from the paper showing a tail from an adult enantiornithine on the left and the baby on the right.

Both of these characteristics are slightly different than in other enantiornithines and in modern birds. This tells us that though very similar to modern birds on the outside, enantiornithines were developing their skeletons slightly differently. Ultimately, this could shed light on the different developmental strategies that we see in modern birds (how some can walk or fly at hatching and some take weeks or years to mature fully).

Figure 7 from the paper showing a reconstruction of the baby bird. The silhouettes show how big the baby would have been compared to a cockroach of the time. By R. Martín.

The Mystery of the Upside-down Ankylosaurs

Many ankylosaurs, the armored dinosaurs, have been found upside down when they’ve been discovered, especially when they’ve been found in river beds or marine sediments. Researchers have had different ideas as to why this might be the case.

An anklosaur. From here.

A new [study] tested several hypotheses to figure out which is the most likely to explain the upside-down fossils. The authors tested 4 hypotheses. The first was the ankylosaurs were just clumsy and would fall down hills and land upside down. This idea is hard to test, and seems unlikely, so the authors moved on.

Turtles can actually flip themselves over when they’re on their backs (though it’s nice to have help from a friend). Ankylosaurs would not have been so successful if they could not do the same.

The second hypothesis was that predators would flip the ankylosaurs over and eat them, leaving the remains to be preserved upside-down. The authors examined 36 ankylosaur specimens and only found 1 with any tooth marks on it. They rejected this hypothesis, since it did not seem that the upside-down ankylosaurs were eaten.

A picture of an ankylosaur being threatened by a T. rex. By Eldar Zakirov.

The third hypothesis was that dead ankylosaurs would wash into a river. Once there, it would start to decompose. The process of decomposition releases a lot of gas, which gets trapped inside the body of the animal, causing it to float. The armor on the back of an ankylosaur would weight more than the gas-filled belly, and the whole dinosaur would flip upside-down. Eventually it would settle to the bottom and be preserved upside-down. To test this, the authors created computer models of a bloated ankylosaur and a bloated nodosaur (an ankylosaur with no tail club). They found that the nodosaur would tip very easily and would flip over more readily. The ankylosaur had a more difficult time flipping over.

Figure 3 from the paper showing the bloated ankylosaur and nodosaur. The plus and diamond symbols are place markers for the computer simulations to test how easily they would flip over.

The last hypothesis was that the ankylosaurs would roll over as the decomposed on land. The authors tested this by examining road-kill armadillos and by watching 22 armadillos decompose in a more controlled setting. They did not find support for this hypothesis as the armadillos were equally likely to be found on their sides, stomachs, and backs.

Armadillos are pretty cute.

The authors concluded that the most likely scenario is that the ankylosaurs would get washed into a stream or into the ocean, bloat from decomposition, and roll over as they floated along. Once the gases escaped, they’d sink to the bottom and get fossilized. This study took it upon itself to test a long-standing idea that had never been tested. Now we have a better notion for how ankylosaurs were preserved and more about their biology.

A Fossil Fight

A couple of weeks ago, 2 articles were published by different research groups about a species of arachnids. Arachnids are the group that contains spiders, scorpions, ticks, mites, harvestmen, and a couple other groups. They all have 8 legs, 2 body segments, and 2 other pairs of appendages that serve a lot of different functions.

The diversity of arachnids. From Encyclopedia Britannica.

The articles focused on 4 specimens of a new species, called Chimerarachnae yingi. ‘Chimera’ means ‘a mixed animal’, ‘arachnae’ refers to the arachnid group, and ‘yingi’ is in honor of the person who found the specimens. All 4 specimens were found in amber in Myanmar and date back to the mid-Cretaceous (around 100 million years ago).

One of the specimens used in the studies. From Wang et al. 2018 (the first group).

Each research group looked at the specimens and ran an analysis of evolutionary relationships to see where this new species fits in. [One research group] found that this species is more closely related to spiders. [The other research group] found that it’s more closely related to an extinct group of arachnids called Urareneida.

The different positions the new species takes. The first study showed that it was closer to spiders (in blue) and the second showed that it was a Uraraneid (in red).

But why the difference? It seems the combination of traits that Chimerarachnae has makes it difficult to clearly place into the tree of arachnids. When analyses are run in slightly different ways, its position moves around. Hopefully more specimens can help clear this up in the future.

NASA and the Lower Cretaceous

The National Aeronautics and Space Administration (NASA) usually has their eyes on the sky, but this week, a [paper] came out that described a fossil found at their Maryland Space Flight Center.

Figure 1 from the paper showing the location of the NASA Goddard Space Flight Center (NASA/GSFC) in Maryland. The different shades of grey indicate different rocks.

Ray Stanford was dropping off his wife, Sheila, back at NASA after having lunch together, when Ray spotted an interesting rock. As an amateur paleontologist, Ray went to investigate. He noticed this rock had a 12-inch-long footprint preserved on it and called on a few professionals to help excavate it. That was back in 2012, and this week, the paper describing this fossil has been published.

The rock slab is 8 feet (almost 2.5 meters) long and 3 feet (almost a 1 meter) wide and shows almost 70 tracks of different animals. The rock is from the Lower Cretaceous (142-96 million years ago) and preserves footprints from theropod, ankylosaurian, and sauropod dinosaurs, and pterosaurs.

Figure 3 from the paper showing the slab on top and the interpretation of the footprints below. The big, purple sauropod print is what Ray had spotted.

But the real stars of this slab are the mammal tracks. Cretaceous mammal tracks are extremely rare, and this slab seems to preserve 26 tracks made by mammals. That’s an incredible amount!

Figure 6A from the paper showing a close up of the mammal footprints on the slab.

Without any body fossils, it is hard to pinpoint exactly what species made these tracks, but further studies and new discoveries could eventually help to figure this out. What this slab does indicate is that Maryland had a very diverse set of animals living there at the beginning of the Cretaceous.

Cheetahs, Ears, and High-Speed Chases

I’m back! I spent the last two weeks of December and a lot of January finishing and sending out She Found Fossils, the [book] about women in paleontology that Abby West, Amy Gardiner, and I wrote. I also went to the annual Society of Integrative and Comparative Biology conference in San Francisco and learned a ton. Now hopefully I can get back to a once-a-week schedule for this blog.

Last week, a [paper] was published that looked at the ears of cheetahs and their cat relatives. Cheetahs are the fastest land animal of today. They’ve got spots and face stripes and little manes when they’re babies.

A cheetah with her cub. From BBC.

Cheetahs are specialized in running at high speeds to chase down small antelopes. Their whole bodies are adapted for running: they have deep chests for bigger lungs and more oxygen flow, flexible backs to make their strides longer, long tails that they use to turn, and their claws don’t fully retract so that they can grip the ground better. All of these traits help them run down their prey.

But when did cheetahs get so fast? This new study looks at their inner ears. The inner ear doesn’t help us with hearing, instead it tells us how quickly and in what direction our heads are moving. It also works with the visual system in the brain to help stabilize the head so that what we see stays steady instead of blurry.

The parts of the ear. The inner ear has is the portion that deals with balance and head movement. From here.

This paper used CT scanning to look at the inner ear of cheetahs, other large cats (like lions and pumas), and 1 species of fossil cheetah. By analyzing the size of the different parts, the authors figured out how much each cat was adapted to high speed running. The bigger the components of the inner ear, the better the cat would be at keeping vision stable at high speeds.

The inner ear of the extinct (middle) and modern (lower) cheetah. You can see how the modern cheetah has wider and larger components than the extinct cheetah. Illustration by M. Grohé.

The authors found that the modern cheetah has larger inner ear components than the fossil cheetah. This means that the fossil cheetah was probably not specialized for high speed running, and that high-speed chasing has evolved more recently in modern cheetahs.

A smiling cheetah. From the Caters News Agency.

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