Sunday, March 18, 2012

Dino Discoveries in a Nutshell

OK. I know I haven't been to good at keeping up-to-date with my dinosaur discoveries, but I've decided to make up for it in this post. I will list every dinosaur discovery from the previous month and include details on my thoughts about them, starting from the beginning:

Nemegtomaia barsboldi doing what Oviraptors do best.

Nemegtomaia barsboldi represents the fourth known genus of Oviraptorid found on nest, and the first unearthed with a preserved skull found intact with the specimen, expanding brooding behavior to yet another species of Oviraptor. Oviraptors themselves are very interesting animals, from the shape of their jaws we don't quite know what they ate, but it's widely accepted that they were omnivores, eating all kinds of plants and animals. Recent discoveries from China show that many were covered in feathers and had excellently large tail feathers, like those of a Peacock. Many species also had a odd form of crest along the mid-line of the snout, far to fragile for butting, it was likely used for display like a modern cassowary.

For a long time however, Oviraptors were erroneously referred to as plain, reptilian egg thieves. This was assumed with a discovery in the early 1900's of a individual apparently caught-in-the-act of stealing another dinosaur's eggs when it died. Thus, it became famous as a pilfering dinosaur, stealing eggs to gain nutrients from the nutrient yolks, and getting the name Oviraptor (Egg Thief). Now, with the discovery of more Oviraptors on top of nests, we found that the eggs actually belonged to Oviraptor, and not another dinosaur, and that the apparent egg-thief actually died protecting it's own eggs, being a good parent. Now Oviraptor is used to help promote the idea that dinosaurs were active, intelligent animals (most people agree with this idea nowadays).

However, Oviraptorid nesting habits are among it's most interesting things scientists have studied, and became even more interesting in 2008 after the discovery that these animals could only lay 2 eggs at a time; yet, you can find over 12 eggs per each nest. Their are two explanations for this, one is that females laid 1 - 2 eggs daily over a long time period, which would take a considerable amount of energy from a female and would cause her to need to feed constantly to re-gain energy. Or, the nests are a sign of a sophisticated social structure where multiple females lay their eggs in a single nest.

This might sound like an odd strategy, but it's a strategy used by modern day ostriches. A single male Oviraptor could make a nest with eggs and attract a harem of females that he mates with. Within a day, all the females lay their eggs within the nest and will typically move off afterwards, and the male is left with the role of protecting the eggs and young. That would mean that this Nemegtomaia is actually a father, not a mother. So far, it's one of these two breeding methods that scientists find likely for the Oviraptorids, but we will probably never know.

Link to Discovery: Fossilized Dinosaur Parent Found

T-rex seems to have had a bigger bite than we gave it credit for.
Research at the University of Liverpool has apparently given evidence to confirm Dr. Greg Erickson's earlier theory that T-rex had a stronger bite force than we gave it credit for, possibly having a bite that dwarfed any terrestrial animal. The study suggests that we've seriously underestimated T-rex's chomping power, which was originally thought to be in the range of 2-3 tons, about half as much as this study suggests.

Earlier estimates that T-rex had a bite force of 2-3 tons, but given the size of the animal, thought to weigh more than 6-7 tons with recent studies, the researchers suspected that its bite may have been more powerful than this. The Liverpool researchers developed a computer model to reverse engineer the bite of T-rex, a method that has previously been used to predict dinosaur running speeds (which I mentioned previously in my T-rex: Predator or Scavenger post).

They then put in the animal's jaw muscles, and made a range of alternative muscle values, as it is unknown precisely known how large the jaw muscles of Tyrannosaurus may have been. Even with error margins factored in, the computer model still showed that the T-rex had a more powerful bite than previously suggested. The smallest values showed a bite force a little under 3 tons, while the largest values showed a bite that exceeded 6 tons of force.

What they also found (that I personally found very interesting) was that the juvenile Tyrannosaurus in their study had a much weaker bite than the adult. This should be expected due to it's smaller body size, but even if you were to scale up the juvenile to the size of the adult, it would still not have anywhere as strong a bite. This suggests that juvenile Tyrannosaurus didn't need their jaws as much as their parents, but instead, juveniles had much longer legs and arms than adult Tyrannosaurus, andthese features may have had a larger role in their lives than the skull and jaws of adults.

This is a very interesting discovery, and probably one of the more interesting ones made this year. Some may argue that T-rex used it's powerful bite to kill prey, and others might think that it was used for breaking bones to get to the rich marrow within carcasses. Weather or not T-rex was a witty scavenger or a fearsome predator, everyone can agree that T-rex had one mean bite.

Link to Discovery: T-rex has most powerful bite of any terrestrial animal

Look out Dinosaurs....

Welcome to your dog and cat's worst nightmares. It seems that China during the Middle Jurassic housed a good number of extinct flea species that were recently unearthed. One species to simply put it, was a complete monster. An inch long species of flea with saw-like mouth parts and murderous intent, and likely spent their days feeding off the blood of giant dinosaurs.

However, these fleas weren't like your typical dog or cat fleas. For one they had a disproportionately long proboscis with a saw-like edge to it, unlike a modern day flea's proboscis which is short and has a smooth edge to it. This might have evolved to dig deeper into the skin of giant dinosaurs, which might have had skin thicker than elephants. The second difference is a more favorable trait though, they didn't have the ability to jump their enormous gaits. These giants had yet to evolve the feature that makes them so famous nowadays, instead they almost entirely crawled to find a meal.

But how could a giant flea such as itself possibly catch up to a dinosaur simply by crawling? I favor the idea that they were more like ticks than modern fleas, waiting on leave or branches for dinosaurs to come walking along. Once in position, the flea would then drop down onto the unsuspecting dinosaur and start probing it for blood. It would definitely be a lifestyle that suited such creatures.

Another surprise though is the time period that they lived in. According to some recent studies of the Mesozoic atmosphere, the time period that these fleas lived in had a low oxygen content. In fact, during most of the Jurassic the earth had lower oxygen levels and higher carbon dioxide levels in it than today, which typically encourages insects, arachnids, and all forms of invertebrate to lose their large sizes.

The reason why is that insects breath through tubes throughout their body, and their sizes are directly linked to how high the oxygen content in the atmosphere is. Thus, during times when the atmosphere is filled with oxygen, invertebrates tend to grow large, but once it gets low again, their sizes start to decrease. Low oxygen content in the Jurassic would encourage smaller insects if anything, yet during these time periods we have giant dragonflies, large spiders, and now giant fleas. Maybe more discoveries in the future will solve this paradox.

Link to Discovery: Dinosaurs had Fleas too - Giant Ones

Velociraptor seems to have had a taste for Pterosaurs

OK. Do Raptors have some kind of thing against flying animals? First we find a Pterosaur wing with a Saurornithoides tooth hanging out of it, then we find a Microraptor with a bird in it's gut, now we found a Velociraptor with a Pterosaur in it's stomach. Why? Were they jealous of them? Did they like the taste of flying animals or something? Was their craving for flying flesh what drove them into the sky?

Nah, just joking there. Though all these discoveries prove that Dromeosaurids were very good predators if they could kill flying prey animals. The recent discovery of the Pterosaur bone lying in the stomach cavity of a Veolociraptor proves this case even more. The fossil, originally recovered from the Gobi in 1994, shows a well preserved 7.5 cm long Pterosaur bone lodged in the upper part of the Velociraptor's ribcage, right where its stomach would have been.

The discovery also shows that Veolociraptor was quite capable of swallowing large bones, something we see in modern day crocodiles and many types of vulture. However, what I don't quite understand is the fact that the scientists that wrote the paper continually say that the Pterosaur was scavenged, and downright deny the possibility that it was hunted.

While their is the possibility that it was scavenged, their is still a good chance that it was hunted as well. They continually say that a Pterosaur with a 6 foot wingspan was too large for a Veolociraptor to kill, yet it likely weighed more than the Pterosaur, and we know that Veolociraptor preyed on animals that weighed a lot more than itself. Remember the Fighting Dinosaurs anyone? If the Pterosaur was maybe 12ft+ then I would believe that it was likely scavenged. But the fact this particular Pterosaur is not that large makes me believe it could have also been hunted.

Link to Discovery:

Microraptor shows it's true colors
Now onto another little bugger that we found another flying animal inside of, Microraptor. A few months ago a fossil discovery showed that Microraptor preyed on birds, and now this study has shown that this little dinosaur, no larger than a crow, actually looked quite like one. In fact, this study has changed much of what we though Microraptor looked like.

Microraptor was originally portrait as a dinosaur with bird-like features, such as feathers and wings. Now with this new recreation, if think you might have trouble distinguishing it from a bird. The new study suggests that it's entire anatomy was more bird-like than expected, especially it's plumage. Microraptor was black, but it's coloration had a twist, it's feathers are the first example of iridescence in both the fossil record, and in feather evolution.

Iridescence is a feature in bird feathers that makes them shine in light, and is typically used for signaling to other members of a bird's species. While Microraptor was probably using the same tactic with it's feathers, it also has a secondary function of strengthening the feathers by organizing melanosomes in stacked layers. This would be very helpful for these early gliding dinosaurs, and earlier this year Archeopteryx was also found to have black feathers. Black pigment is typically strong and durable, and would also strengthen the feathers of dinosaurs and early birds..

Another surprise was that the tail feathers of Microraptor had been erroneously portrait over the last 10 years. Originally, the feathers at the end of the tail of Microraptor were thought to be teardrop in shape and used as a kind of rudder for turning while in flight. However, now we know that the tail feathers were far more narrow and elongated than originally thought, and two feathers in particular at the tip of the tail were elongated out. These instead of being used as a rudder, were instead likely for show, and evolved for courtship behavior and other social interactions.

In fact, these two elongated tail feathers bring to mind the tail feathers of another extinct feathered animal. Confuciusornis was a bird that lived at around the same time as Microraptor, and was a true bird rather than a dinosaur. Still, it was a rather primitive bird, with claws on it's wings, teeth in it's beak, and like Microraptor, two long streamer-like tail feathers. In Confuciusornis however, they were much longer and attached to a much shorter, bird-like tail rather than the long tail of Microraptor.

It's interesting to note that some specimens of Confuciusornis lack these tail feathers, suggesting that it was a sexually dimorphic trait, and that males likely possessed them to attract streamer-less females. Microraptor, was different though. The scientists studied 9 Microraptor specimens and found the tail feathers present on all of them, suggesting that it wasn't dimorphic, and rather both genders had them. Meaning that the tail feathers likely had a purpose beyond mating displays.

Link to Discovery:

An illustration of Unescopceratops (Top) and Gryphoceratops (Bottom)

And now for probably what you've all been waiting for: What are the newest dinosaurs of 2012? Well they aren't big, in fact one of them might be among the smallest of all Ceratopsian dinosaurs, but they are definitely interesting. I introduce to you all the new species, known as Unescopceratops koppelhusae and Gryphoceratops morrisoni. Both are two new species from the Leptoceratopsidae family of horned dinosaurs, and represent some of the earliest forms of the group known.

Unescopceratops was the first of the two found, and lived roughly 75 mya in the Dinosaur Park Formation of Alberta. Unescopceratops was about 6 feet long and weighed less than 200 pounds. Unescopceratops is sadly known from only a left lower Mandible, but like other Leptoceratopsians, it would've probably had a short frill extending from behind its head, a short parrot-like beak, and might have possessed the ability to run on two legs for quick bursts of speed. Unusual for a Leptoceratopsians though, was the fact that below it's lower jaw it had a distinct portion of bone that projected below the jaw like a small chin. Giving it an interesting look among ceratopsians in general.

The lower jaw of Unescoceratops was discovered in 1995, but was only described along with Gryphoceratops (who was found in 1950) in a recent paper. Unescoceratops' strange name comes from the United Nations Educational Scientific and Cultural Organization (UNESCO), which helped discover the locality where the specimen was found. The species name however, was named after Eva Koppelhus, wife of Philip Currie who helped name the specimen.

Gryphoceratops morrisoni is another very interesting member of the Leptoceratopsidae. It is also only known from a lower Mandible and was also found in the Dinosaur Park Formation of Alberta, but this specimen is older, about 83 million years old, making it the oldest Leptoceratopsian known (which means the illustration above would've never happened). Ironically, a cladistic analysis showed that it was actually among the most advanced Leptoceratopsians, and not a primitive member of the group, which must mean their are older more primitive species of Leptoceratopsians still to be discovered.

Another ironic thing about Gryphoceratops is the fact that it's also the smallest member of the ceratopsians known from North America, less than one and a half meters in length. We know it wasn't a juvenile because the bones in the jaw were fused, suggesting it was an adult. Based on what we know of Leptoceratopsians, it probably was fairly typical looking and other than the head, wouldn't be something you looked at for too long on a Safari or Zoo Trip, unless you look closely at the lower jaw.

Gryphoceratops had a shorter and deeper jaw than any other leptoceratopsid, giving it a distinct look. Deep lower jaws are seen in some species of dinosaurs, such as Shantungosaurus, a giant species of hadrosaur from China. It's still unknown what evolutionary advantage a deep lower jaw is for, but some have suggested that it might have something to do with a grazing lifestyle. Of course, they wouldn't be grazing on grass, modern types of grass hadn't evolved yet, instead they would be grazing on small ferns that took the place of grass during the Cretaceous.

Gryphoceratops was named after the "Gryphon" of Greek mythology. A creature with the body of a lion, the wings and head of an eagle, and the tail of a serpent. It only seems fitting as some scientists believe that the Gryphon myth first came up after the discovery of Protoceratops bones in Mongolia. The species name name honors Ian Morrison, a Royal Ontario Museum technician who was friends with the discoverers.

Link to Discovery:

Now with that out of the way, I'll be free to make some more interesting topics for everyone to read. As always, feel free to speak your opinion, I'll be happy to take requests for topics, and make sure to stay sharp!

1 comment:

  1. Gee, such a nice long article!

    I've read about these somewhere few days ago. I'm surprised they take it as fact that velociraptor scavenged on that pterosaur, though it's probable, we can assume that it could also hunt it down without much trouble.

    I remember my old books saying "We will never know what colours these scaly beasts had". Well, as I said, OLD books. First they recieve feathers, now we're able to determine some of their actual appearances. I'm waiting for another breaking discoveries about what new info can we extract from fossils :>

    Again, congrats on the article!