On December 7th, 2017 we learned about

Elephant feet provide context in studies of extinct sauropods’ footprints

To understand how extinct dinosaurs functioned in the world, paleontologists often look to living animals for examples of how similarly built creatures put their modern anatomy to use. For example, the thick, columnar legs of an elephant seem like a good reference point for how ancient sauropods might have lumbered around.  Looking beyond bones, researchers are thinking that modern elephants can also be a reference point for trace fossils, like footprints made back in the Mesozoic era. While sauropod dinosaurs haven’t shared a direct ancestor with elephants for over 100 million years, the hope is that the similarity in their ecological niches as giant herbivores will carry over into other aspects of each animal, right down to the bottom of their feet.

In South Korea, a fossilized footprint revealed a very specific similarity between elephant and sauropod feet. The trace fossil footprint was covered in a sort of honeycomb-shaped pattern, as soft mud crept into the cracks of the dinosour’s feet way back in the Cretaceous period. The resulting texture shows the dinosaur’s feet were covered in hexagonal scales across their soles, looking strikingly similar to the natural tread found on an elephant’s feet. It’s hard not to assume that this was a case of convergent evolution, with both large herbivores evolving the same “solution” to keeping thick, heavy limbs from slipping as they walked through soft soil or wet mud.

Inferring size from a foot’s impression

A second study looking at sauropod footprints wasn’t focused on the texture of the dinosaur’s soles as much as what those prints could tell us about the animal as a whole. Starting with the simple premise that heavier animals will make deeper footprints, researchers measured fossilized tracks and then simulated the forces that would be needed to make different sizes of footprint. Once a match could be made between simulated feet and the depth of actual fossilized prints, researchers could then calculate just how much the original sauropod must have weighed to sink that far in the soil.

To validate this method, they turned to elephants as the closest living approximation for extinct sauropods. Researchers used the same techniques developed around fossilized prints on fresh elephant footprints, since they could then verify the living elephant’s weight. In the end, the simulated footprints weren’t perfect, but with a margin of error of around 15 percent, they were at least as close as other methods for estimating dinosaur mass. For example, estimates for a dinosaur’s size may be made calculating the animal’s volume based on bone sizes, which in turn is often based on living animals as reference points. The hope is that estimates based on footprints can be refined to become more accurate, particularly in regards to the physics that control soil movement.

Restraint in using elephants as reference points

Other researchers question the validation aspect of this technique though, since we can’t be sure if elephants really are the best reference point for animals that could grow to be close to 100 feet long and probably weigh ten times more than the largest living pachyderm. Differences in leg movement, for instance, could change how weight is distributed across a dinosaur’s heels and toes, which could affect how deep a foot presses into the dirt. These critics aren’t advocating that giraffes or rhinos would necessarily be a better model organism, but that we should be careful about assuming too much about how sauropods were built and moved, even if their feet now seem so familiar.

Source: Can fossil footprints reveal the weight of a dinosaur? by David Moscato, Earth Magazine

On December 6th, 2017 we learned about

Halszkaraptor escuilliei, the first known dinosaur (partially) adapted to an aquatic lifestyle

It wouldn’t really do Halszkaraptor escuilliei justice to say the newly described dinosaur “broke the mold,” because this unusual animal seems to have been the product of three or four molds mashed together. While technically a theropod dinosaur, like Tyrannosaurus or Velociraptor, H. escuilliei followed very few of the anatomical conventions laid out by its relatives. Instead, the resident of what is now Mongolia sported features only seen on more modern relatives, like the neck of a swan, or the upright posture of a duck. The overall package was so unusual that paleontologists studying H. escuilliei‘s fossils weren’t even sure it was a legitimate specimen when it was first presented to them.

An artificial amalgam, or just really odd?

Paleontologists usually find fossils themselves, either in the field or at least in a museum’s archives. Appropriately for such a weird species, H. escuilliei was handed over to researchers at the Royal Belgian Institute of Natural Sciences after it was purchased from smugglers on the black market, with the eventual goal of repatriating it to Mongolia. This sordid history, plus the strange mix of anatomy, necessitated extra scrutiny to make sure the 15-inch block of stone contained fossils from one animal, as fossil poachers will sometimes glue fossils together to basically fabricate a more exciting specimen. Since H. escuilliei already looked like a mix of at least two to three animals, researchers felt it warranted a trip to the European Synchroton Radiation Facility (ESRF).

Using the multi-resolution tomographic scanning, researchers were able to comb over every inch of the fossils and rock that contained the specimen. Rather than finding suspicious cracks and glue, the high-energy x-rays from the synchroton showed that the bones were consistent in their composition throughout the skeleton. This confirmed that the skeleton had not been altered by humans, and was simply exotic looking due to evolution.

Mostly set for going swimming

The synchroton also allowed researchers to assemble a highly detailed, 3D digital model that let them examine details without damaging the rock or fossils in the process. Peering through the 3D structure, they found an unusual number of skinny teeth towards the front of H. escuilliei’s mouth. Scans also revealed spaces for a network of sensory nerves, reminiscent of a crocodile’s sensitive snout. The nostrils were located higher on the snout than most ancient theropods, placed in a location closer to where you’d find them on a modern duck. Finally, the head was noted for being especially triangular overall, all of which seemed to indicate that H. escuilliei wasn’t running down food on land like its kin, but was instead snatching fish from the water.

Imagining H. escuilliei moving through the water was a little weirder than figuring out how it fed. The dinosaur had an elongated, flexible neck which has been compared to a swan’s. However, the arms certainly didn’t allow for flight like many waterfowl today, and they weren’t quite as specialized as a penguin’s flippers either. The fingers were elongated differently than other ancient theropods, instead looking like the shape of a bird like a murre. Researchers suspect that these forelimbs were used like paddles in the water, although without more information about the shoulders, it’s hard to know how well they could really move. At the very least, the feet and legs don’t match the efficient webbed feet found on a modern duck or goose, instead being more suited for simply walking around on land.

Aquatic but kind of awkward

The overall impression of H. escuilliei seems to be a jack-of-all-trades, and master of none. The dinosaur was at least partially equipped for the water, but not completely committed to it to the degree modern shorebirds are. The small predator could walk around on land, but probably collected most of its food paddling around lakes or swamps. This may indicate that H. escuilliei’s environment was in a state of flux, and that the water it preferred wasn’t always available. As a result, it still had to be ready to walk to the next pond to look for more fish.

Finally, the last weird thing about this dinosaur is that it’s weird at all. Mammals can be found in the air, in trees, underground, and in the oceans. Dinosaurs came in all shapes and sizes, ruling the Earth for millions of years, but somehow skipped going for a swim in all that time. We don’t find many theropods in the shape of H. escuilliei, but this creature’s existence begs the question as to why that is. Are more aquatic species still waiting to be discovered, or did dinosaurs have some other reason to avoid committing to living on the water?

Source: Apparently This Is What a Swimming Dinosaur Looks Like by Ed Yong, The Atlantic

On November 30th, 2017 we learned about

Destroyed Hamipterus colony yields unique views of pterosaur embryos, growth and development

120 million years ago, disaster struck a pterosaur nursery in what is now northwest China. What was likely a huge, sudden storm washed hundreds of nesting pterosaurs out of their nests, burying them in a jumble of fine sand and silt. While it was certainly a terrible way to die, the water and silt did an amazing job of preserving huge swaths of the nesting colony’s population, from young animals to old. Most remarkably, some of the soft-shelled eggs of Hamipterus tianshanensis tore open, allowing silt to enter and envelop developing embryos, saving them from being crushed and flattened in the fossilization process.

Delicate structures preserved in sandstone

Paleontologists have found and studied prehistoric eggs before, but finding developing pterosaurs is especially rare. Even adult pterosaurs have thin, hollow bones that make flying easier, but aren’t especially durable when buried in rock for millions of years. Embryos developing in soft, lizard-like eggs are understandably rarer, making this particular cache of fossils a unique opportunity to learn about pterosaur life cycles. A nine-cubic-foot block of sandstone is still being studied, but researchers believe it contains bones from H. tianshanensis of all ages, as well as up to 300 eggs.

Not every egg survived the rough process that swept them out of what was probably a nesting colony, similar to what some bird species use today. Out of the 215 eggs extracted, 42 retained their original dimensionality enough to scan, and 16 had developing embryos to study. To examine these delicate structures without damaging them, researchers employed computerized tomography, essentially letting them build a 3D model of the shapes still encased in sandstone.

New details on pterosaur development

These fossils have also sparked a somewhat controversial conclusion about these pterosaurs’ growth patterns. A particularly mature embryo was judged to be close to full term, but surprisingly didn’t have fully developed deltopectoral crest bones on its wings. In contrast, it did have some full-strength femurs, raising the possibility that these pterosaurs could only walk when they first hatched, waiting to fly until they’d had a chance to grow up a bit. This is in contrast to other studies from other species, and probably can’t be resolved until more embryos can be found. Otherwise, it’s hard to say if this single specimen represents the development of all pterosaurs, all members of its species, or even if it was as close to term as the study’s authors speculate.

With so many individuals crammed into a single block of limestone, we should have more details to how pterosaurs grow up. Many researchers agree that the diversity of ages seen in this collection is strong evidence of communal nesting. The variety of ages also suggest that nesting season was at least long enough for some babies to hatch before their neighbors were still incubating in their eggs. As much of a calamity as the original storm was for these pterosaurs long ago, their well-preserved deaths will soon give us an incredibly clear picture of a H. tianshanensis‘ life cycle.

Source: Huge haul of rare pterosaur eggs excites palaeontologists by John Pickrell, Nature News

On November 29th, 2017 we learned about

Dinosaur’s unusual feathers maximized fluffiness over all other functions

A penguins’ feathers help insulate its body. An eagles’ primaries can form a surface to create lift. An Anchiornis‘ feathers…well, that’s difficult, because nobody has ever seen this Jurassic period dinosaur make use of its plumage. Complicating things further, Anchiornis‘ feathers were a very odd shape, deviating from the fluffy down or stiff primaries you see on modern birds. According to paleontologists from the University of Bristol, one of the most striking effects of Anchiornis‘ odd feathers was simply how floofy they must have made this dinosaur look.

Your average flight feather on a bird today is stiff, with the vanes coming together to form a single plane that can contribute to creating lift, or at least help streamline a bird’s silhouette. Some feathers, like the decorative plumage found in peacock’s tail, are looser, fanning out while still retaining a unified shape. Anchiornis seems to have been an evolutionary experiment, with a feather shape that doesn’t seem to have withstood the test of time. Instead of a tapered tip, the vanes in this dinosaur’s feathers split in two distinct directions, forming a “V” shape. En masse, it would have made for a fluffy, uneven profile, with the tufts of thick fluff covering the paravian dinosaur’s whole body.

Purpose of poofy plumage

These feathers wouldn’t have been great at creating lift like the flight feathers on a modern bird’s wing, but that doesn’t mean that Anchiornis was stuck on the ground. It actually had wings on it’s arms and legs, each with multiple layers of feathers to help catch the air. It wouldn’t have been capable of powered flight, but probably could glide between trees on these thick, fluffy wings. The fluff would have also created a lot of drag in the air, so Anchiornis was also adept at grasping at tree branches, looking more like a shaggy monkey than the robins, crows and parrots we can see perched in trees today.

One thing Anchiornis‘ feathers could do as well as their modern counterparts is to provide coloration. Sure, crisp lines and detailed markings may have been a bit of a stretch, but previous studies have found evidence of the pigments that once colored this creatures’ floof. Wings were likely light, with dark spots along feathers’ “tips,” while the majority of the body was a dark gray or black. These colors may have served to impress peers, but likely also resembled the dappled light and shadows that would have been found in Anchiornis forest home. Obviously, modern birds prove that the “V” shape feathers weren’t strictly necessary to remain camouflaged or soar through the air, but evolution doesn’t always iterate along a single design path.

Source: Feathered dinosaurs were even fluffier than we thought, Phys.org

On November 27th, 2017 we learned about

Most of the mammoths found trapped in hazardous terrain turn out to be male

One of the most important features of the La Brea Tar Pits in Los Angeles are the traffic cones. The museum’s collection of Pleistocene animals is great, as are the continuing excavations taking place at the site, like Project 23. However, having just returned from my kids’ first visit to the Tar Pits, I think the entire experience was greatly enhanced natural liquid asphalt bubbling out of the ground in the surrounding Hancock park. Some bigger pools are fenced off, but it’s clear that the asphalt is slightly unpredictable, sometimes oozing outside a barrier, or simply popping up in the middle of the lawn, with only an oil-splattered traffic cone to warn you of its sticky presence. It all helps drive home just how animals living in the Los Angeles basin 60,000 years ago might have gotten into trouble without the bright green cones in place to warn them.

The La Brea Tar Pits weren’t the only natural hazards Ice Age animals had to worry about, and a recent study of mammoth (Mammuthus primigenius) remains from Siberia looked for patterns in which creatures most often got themselves into these sticky situations. Excavations of geological dangers like asphalt pools and icy lakes had already established that one trapped herbivore was likely to attract huge numbers of carnivores (that would also end up trapped), but this study looked to see which particular mammoths couldn’t stay out of the asphalt, ice or other pitfall. Since these animals were well preserved from only 60,000 years ago, DNA from hair and bones could be used to determine that 69 percent of the trapped mammoths were male, despite having originated from a balanced population.

Males in the muck

Researchers suspect that, if mammoths follow some of the behaviors seen in their modern elephant relatives, the unusual sex-ratio was due to male mammoths’ inexperience. Elephants today generally rely on the leadership of an older female, and that matriarch retains and transmits information about everything from when to migrate to how to avoid hazards in their environment. Young male elephants have to figure all this out themselves, even if it means finding out the hard way.

If mammoths lived in a similar manner, the males likely fell into pits and asphalt pools more often because they had nobody to teach them until it was too late. A higher tolerance for risk may have also made them more likely to try stepping on the weird black stuff in the grass, since without a matriarch or green traffic cone to warn them, they weren’t sufficiently wary of what now seems like an obvious danger.

My third grader asked: What’s the asphalt made of?

liquid asphalt bubbling up in Hancock Park
Liquid asphalt bubbling up in Hancock Park, Los Angeles.

While male mammoths were apparently adept at getting stuck in all kinds of hazards, the pachyderms in what would become Los Angeles were stuck in a natural asphalt, which is the lowest grade of crude oil. This oil is a layer of decomposed, pressurized marine plankton, first laid down five to 25 million years ago. The bubbles are generally methane gas, although microorganisms in the oil help create hydrogen sulfide, which adds a notable “rotten egg” smell.

It’s not clear how ancient mammoths missed the bubbles and the smell, but once dust and leaves covered the surface of a shallow oil pool, it seemed to only take a few steps to completely ensnare mammoths and other megafauna.

Source: Woolly Mammoth Bachelors Skew the Fossil Record by Carl Engelking, D-brief

On November 16th, 2017 we learned about

Composition of coal deposits suggests that plants benefited from dinosaur defecation

Plants love giant herbivores. It’s not that they are dying to be devoured exactly, but big eaters like a modern buffalo or ancient Diplodocus have historically helped disperse resources that plants need throughout an ecosystem. By eating plants and seeds, these unintentional gardeners break down nutrients in their digestive system, pooping them out on fresh soil in a new location. Plants’ dependency on this fecal fertilization is sometimes obvious, such as with the impossibly large pit of an avocado that evolved in conjunction with huge creatures like the giant ground sloth, Megalonyx. Other aspects of this dynamic, like nutrient distribution, are a bit more elusive, since the only direct record of that process in the herbivore’s poop itself. To study how this relationship may have worked long ago, researchers skipped looking for the poop itself, focusing instead on coal.

Coal is largely made up of carbon from ancient plants, compressed over millions of years into the black rocks we know today. It’s not completely homogeneous though, and significant amounts of other materials from the original plants can still be detected when the coal is analyzed. These data are routinely gathered as part of geological surveys, so when Christopher Doughty from the University of Flagstaff wanted to find out how much over-sized herbivores like dinosaurs impacted their ecosystems, the coal was an attractive data source.

Comparing coal collections

Obviously, nobody can be exactly sure where these huge dinosaurs were dropping their dung, but the fossil record does provide evidence about where dinosaurs were spending their time. Doughty focused his study on two batches of coal deposits, with one being primarily samples from the western United States, dated to the Cretaceous period, and the other coming from Appalachia’s Pennsylvanian subperiod, a time that predated any true dinosaurs by over 40 million years. As expected, the coal, and thus the plants, from the Cretaceous had much higher nutritional levels, with an average of 136 percent more calcium, magnesium, phosphorus and sulfur. These nutrients were also more evenly distributed geographically, indicating that the dinosaurs that were depositing them weren’t congregating for extended periods of time in a single location. Based on the bathroom habits of modern herbivores, Doughty estimates that a multi-ton herbivore was likely to walk between four to 10 miles before taking needing a rest stop, making sure that no single plot of land got all the nutritious feces.

As much as these patterns make sense, it’s hard to be conclusive about this activity. To rule out non-fecal explanations for the differences between the western and Appalachian coal, like erosion or precipitation, aluminum levels were used as a kind of control. Aluminum is naturally occurring but toxic to plants, so if it was also more prevalent in the Cretaceous coal, it might suggest that these elements were added independently of plant growth cycles. However, aluminum levels were very similar from both batches of coal, indicating that changes in geology and the weather were not responsible for the enriched coal. While it’s not the same as finding a massive collection of distributed coprolites, it does look like dinosaur poop made a big difference to plants’ health.

Plants deprived of dung

So if plants seemed to do better when there were huge herbivores spreading nutrients near and far, where does that leave our ecosystems today? Unfortunately, it looks like human development has broken this dynamic, as we’ve purged many habitats of their plant-eating megafauna. Those that remain are also unable to roam as freely as their ancestors did, which is likely creating pockets of nutrition in places where the buffalo still roam, while leaving other areas less inviting to plant life.

Source: Signatures of Dinosaur Poop Found in Cretaceous Coal Seams by Katherine Kornei, Eos

On November 14th, 2017 we learned about

Ancient otter had a bite big enough to put mollusks, mammals, birds and turtles on its menu

Paleontologists may have identified the most dangerous, and by extension, cutest, otter to ever live. Siamogale melilutra is estimated to have grown to 110 pounds in size, possibly acting as the apex predator in its local environment. This assessment isn’t just based on the otter’s wolf-sized body though, as researchers have also simulated its jaw strength, suggesting that this fuzzy critter could have probably munched just about any animal it got it’s mouth on.

S. melilutra lived around six million years ago in what is now southwestern China. It would have been a wet, swampy area with thick plant growth with plenty for an otter to eat, assuming these carnivores ate similarly to their modern river otter cousins. That’s a wide range of possibilities, as modern otters are known to eat everything from plants to rodents to clams. Once researchers factored in how the size of S. melilutra must have influenced its bite strength, they had to expand the possibilities to include thick-shelled mollusks, birds and even the local turtles if it felt like it.

Baby-faced with big bites

Otter bites are generally pretty impressive, being driven by large muscles in their face that also lead to the cute cheeks people find so adorable. To create a more detailed picture of S. melilutra’s bite, researchers scanned fossilized jaws with computed tomography (CT), getting a picture of the ancient bones inside and out. They calculated the range of the jaw’s movement and how much force it could exert on a crunchy snack, then compared that to similar calculations based on modern otters to see if the results fit with better known otter-anatomy. The overall trend was that smaller otters tend to have smaller, sturdier jaws than their larger kin. However, S. melilutra broke that trend as it’s jaws were six-times stronger than you’d expect for it’s size. Basically, it’s bite was even bigger than it’s already large body.

While calculating the physical forces a skull can exert is helpful, otters tend to complicate matters with their behavior. Most animals’ bites are correlated with the food they need to break apart more than their overall size. If this were strictly true in otters, clam-eating sea otters would have even more enormous jaws than they already do in order to break open hard shells. By using rocks, the otters have come up with an alternative to bigger teeth and jaws, and so their anatomy doesn’t need to match their diets so closely, allowing for the closer correlations with body size. Even allowing for this otter-specific weirdness, the fact that S. melilutra had both larger and stronger jaws still suggests that it was a top predator, as its powerful bite would have put just about everything in it’s environment on the menu, even without figuring out how to break shells with stones.

Source: A giant, prehistoric otter's surprisingly powerful bite by Charlotte Hsu, University of Buffalo News Center

On November 1st, 2017 we learned about

Decennatherium rex prominently placed in the giraffid family tree thanks to the fancy features on its face

Giraffes have neat spots, purple prehensile tongues, and legs so long they can’t drink water from the ground without crouching. Of course, there’s one more piece of anatomy that eclipses all else. A feature that really defines what it means to be a giraffid. Ok, the long necks are neat too, but for members of the Giraffidae family, it turns out that what really counts are ossicones— the skin-covered bumps that look like underdeveloped antlers on the animal’s forehead. It’s understandable if those protrusions aren’t your go-to reference point for these enormous mammals, as the only other living member of the family, the okapi, doesn’t seem like its closely related to its taller kin. However, recently described fossils of some ancient giraffids have helped fill in gaps in these creatures’ evolution, making it clear that those seemingly insignificant ossicones really are the feature that ties the family together.

The ancestor in question is Decennatherium rex, a giraffid that lived in the Miocene epoch, around nine million years ago. They could grow to be around nine feet tall, weighing as much as two tons. This leaves them as a medium-sized family member compared to it’s extant, or surviving, family members, but D. rex did have at least one claim to fame. The recent fossils included unusually well-preserved skulls, letting researchers get a good look at the animal’s four ossicones. One pair grew over the eyes, and the second pair grew up to 16-inches-long between the animal’s ears. The larger set were curved and adorned with ridges, drastically punctuating D. rex‘s profile.

Forks in the giraffid family tree

The detail visible in these fossils has paleontologists carefully examining where D. rex fit in the Giraffidea family. Out of the 30 or so species identified through fossils, two major groups stand out. These are sivatheres, which includes animals that generally had larger ossicones sometimes resembling antlers, and samotheres, which had more modest protrusions on their heads, like modern giraffes and okapi. Researchers now believe that the four ossicones on D. rex straddle the line between both groups, making this species the last shared ancestor between them. If this is correct, these fossils from Spain show that these lineages lived further north and millions of years earlier than previously understood.

That’s a lot to get out of some bony lumps on these creatures’ heads, but D. rex‘s four ossicones challenged one more assumption. Paleontologists believe that they have both male and female specimens, and that both sexes sported ossicones on their heads. This contradicts an earlier hypothesis about the function of ossicones, which suggested that they may have been used for sexual display, much like the large antlers found on modern deer. However, if both sexes had use of this anatomy, they may have served some other purpose as well.

My four-year-old asked: Why are they called okapi?

The name okapi comes from pygmies living in the Congolese rainforest. In Lese Karo, they called the animal o’api, which itself is a combination of oka, meaning “to cut” and kpi, which refers to stripes they would scorch onto the shafts of their arrows. Altogether, okapi are named after the resemblance their butts have to these marked arrows, which they actually use as camouflage in the dense jungles. Early descriptions of okapi often referred to their horse-like traits, making it a surprise when they turned up with the split hooves of an ungulate, not to mention, of course, the ossicones of a giraffid.

Source: This Huge, Four-Horned Mammal Is Rewriting Giraffe Prehistory by Jake Buehler, Gizmodo

On October 26th, 2017 we learned about

A reexamination of the fossil record finds that cockroaches aren’t so ancient after all

According to popular lore, nothing will ever bring down cockroaches. They’ve supposedly been on Earth since time immemorial, and will be hear long after humans wipe themselves off the map. What’s more, they’ll probably continue living in the ruins of our kitchens just to spite us. Unsurprisingly, careful research is finding that the legendary persistence of cockroaches just isn’t true. In fact, some fabled dates of the roaches’ origins appear to be wrong by at least 160 million years.

The story of cockroaches was thought to have started in the Carboniferous Period, over 300 million years ago. It was a time when much of the planet was constantly warm and humid, which admittedly does sound like something a cockroach would be into. Fish were starting to look more like their modern counterparts, but terrestrial vertebrates were just getting started as proto-amphibians. While the world definitely had plenty of insects at this point, as they seemed to evolve alongside some of the first terrestrial plants 479 million years ago, there’s no evidence of true cockroaches. The closest thing would be a confusingly-named group of bugs called “roachoids.”

Roachoids were cockroaches ancient ancestors to be sure. The beetles resembled modern roaches enough to be given the associated name, but they weren’t strictly the first cockroach. In fact, the roachoid lineage was diverse enough that modern cockroaches are more closely related to a praying mantis than the roach-like insects from 300 million years ago. Aside from the name, part of the confusion in differentiating ancient roachoids from true cockroaches is that many fossil specimens were originally misclassified. It’s estimated that only 25 percent of supposedly ancient cockroach fossils are actually cockroaches, and as these identifications are corrected, the age of roaches will continue to be refined and adjusted.

Cockroaches in the Cretaceous

This isn’t to say that cockroaches are the newest bug on the block. Cretaholocompsa montsecana is the oldest known roach, and it was scuttling around what is now Spain in the Cretaceous period 130 million years ago. That makes it a younger lineage than a Stegosaurus, but older than a Triceratops. No matter who its neighbors were, it probably lived in their shadows similarly to roaches around humans, eating and cleaning up after scraps and waste. There’s a fair chance that there were earlier cockroaches as far back as the Jurassic period, but their lineages seem to have gone extinct, with no descendants alive today.

Beyond the trailblazing of C. montsecana, there isn’t a lot of roach diversity in the fossil record until after the dinosaurs went extinct 65 million years ago. Other cockroach species have turned up from 40 and 50 million years ago, and researchers suspect that most modern cockroach species started to evolve around this time period. None of this makes roaches any more pleasant to discover on the sidewalk or under your sink, but it might influence your thinking about just how immutable these supposed living fossils really are.

Source: Old, But Not That Old: Debunking the Myth of Ancient Cockroaches by Dominic Anthony Evangelista and Manpreet Kohli, Entomology Today

On October 19th, 2017 we learned about

New evidence necessitates the reevaluation of species that survived past their supposed extinctions

It seems like it’d be hard to miss an animal the size of a lion named for its serrated, sword-like teeth. An animal like Homotherium latidens, or the European scimitar cat, was once one of Europe’s most formidable predators, at least until 300,000 years ago, when it seemed to have gone extinct. However, a jawbone pulled from the North Sea is rewriting that timeline by 270,000 years, as both carbon dating and genetic evidence suggests it was alive as recently as 28,000 years ago. This younger specimen is now raising a lot of questions, as new causes for extinction, new ecological niches and that giant gap in the fossil record all need to be reconsidered.

Homotherium were like slightly scaled-down versions of their more famous saber-toothed cousins, like Smilodon. Nonetheless, this cat still had two large, canine teeth, and their knife-edge shapes suggest they were probably used for cutting and slashing rather than simply impaling prey. It’s hard to know for sure, because the humans that we now know lived as neighbors to these scimitar cats unfortunately didn’t leave any good field notes behind. Even cave paintings of predatory cats found in norther France somehow omit any solid portraits of H. latidens.

Missing, or migrating?

One of the possible explanations for Homotherium’s absence in the fossil and written record may be that they just weren’t around much. One hypothesis to explain how the cats could be alive without leaving behind more evidence is that they had gone on a very long migration, possibly even around the world. This idea is slightly bolstered by some the fact that the cats’ closest relatives are known to have turned up in North America, although that relationship is also being reexamined.

Looking at the mitochondrial DNA recovered from the new jawbone, researchers were able to not only date the specimen, but also see where it fits in the larger cat family tree. They found that H. latidens is remarkably similar to its North American kin, Homotherium serum— so much so that it’s been suggested that they might be the same species in a new location. This similarity is in contrast to H. latidens’ relationship with other cat species, which forked away from each other 20 million years ago. While they do share a common ancestor, your house cat is more closely related to a modern tiger than Homotherium is to other saber-toothed cats like Smilodon.

Assuming that we’ve now found the most recent H. latidens bone on the planet, scientists now have to think about what caused its final extinction 28,000 years ago. As presumptuous as it sounds, there’s a fair chance that these cats really did go extinct at that point (really!) if only because so many other animals were being removed from the food chain around the same time. Europe was experiencing an ice age at that point and coming to grips with more efficient human hunters. The combined ecological stresses likely explain not only the extinction of these saber-toothed cats, but other megafauna like mammoths and cave bears as well.

Other exaggerated extinctions

Balbaroo fangaroo
Balbaroo fangaroo, who’s name may never be topped

As big an upheaval as this new bone has caused, it’s worth remembering that this isn’t the first time paleontologists have had to rethink extinctions. You can’t predict what fossils will be found, and while most species seem to cluster geographically and chronologically, they can surprise us with their extended survival. Just this month, another extinct mammal with big teeth extended it’s timeline, but by five million years. Fanged kangaroos like Balbaroo fangaroo weren’t exactly impressive predators, as they were browsing herbivores that scurried around ancient Australia, but they apparently did better than we’d previously given them credit for. Like the European saber-toothed cats, the pressures that drove them to their (final!) extinction is now be rethought, since in their case they seem to have outlived their regions major climate crisis known to have taken place 15 million years ago.

Source: This Saber-Toothed Cat Mingled With Modern Humans by Michelle Z. Donahue, National Geographic