DinoBlag: Shonisaurus

(A picture of the animal in question by Dmitry Bogdanov. It doesn't belong to me!)
Finally! A marine reptile gets some time in the spotlight. Shonisaurus is the largest of any marine reptile yet discovered. There are two species within the genus: S. popularis and S. sikanniensis, the latter being the larger of the two at an estimated 69 feet (21 meters) in length. Shonisaurus belongs to the family Shastasauridae within the order Ichthyosauria, and its closest relatives include Besanosaurus and Shastasaurus.

Shonisaurus lived during the Norian stage of the Upper Triassic, and has been found in Nevada, British Columbia, and possibly the Himalayas. It posesses several traits, such as relatively long and thin flippers, which seem to suggest that it does not belong to the main branch of the ichthyosaurian evolutionary tree, and instead belongs to a sort of offshoot from that group.

It posessed several conical teeth which existed only at the front of its mouth, and a rather large body for an ichthyosaur.

Princeton Field Guide to Dinosaurs, etc.

But never mind all that golden eagle business. Look what I got!

It's so beautiful.

The Princeton Field Guide to Dinosaurs is Gregory S. Paul's latest book, and has detailed information on nearly every recognized (and some unrecognized) species of dinosaur, from the tiniest ornithopod to the tyrant kings. Accompanying the book's descriptions are Paul's splendid - as usual - artwork. The book is the most up-to-date dinosaur encyclopedia on the market now, to the best of my knowledge.

The book details the geographic and chronological distribution of the various dinosaurs, the formation they were found in, their habitat, their eating habits, what separates them from their relatives, and other notes. The book is enlightening and scholarly, while simultaneously having the benefit of being accessible to those who are less dino-literate.

I give this book the official SR Seal of Approval, and would recommend it to any lover of dinosaur paleontology in a heartbeat.

In unrelated news, the whole leopard gecko thing kinda fell through. I hope to get one eventually, but for the foreseeable future, I won't be getting one. Need to get the time and money together to buy one.

Meanwhile, in dinosaur-land, a battle is being waged over the fate of Raptorex (shudder), with some alleging that it is yet another juvenile Tarbosaurus (see: Alioramus), and others defending it, on the grounds that a certain ridge on its pelvis distinguishes it from that Asian tyrannosaur.

Personally, I hope Raptorex's name vanishes into the taxonomical trashbin, never to be seen again.

News of supposed Middle Jurassic bird footprints in Africa... Given Africa's scant Mesozoic record, I wouldn't be terribly surprised if this, and other unusual things in the future, may turn out to be true about this paleontological blank spot.

Hopefully, I'll give more updates in the near future and learn to stop slacking off. Wish me luck.

Coming Soon...

Golden eagles kill goats. For reals.

Oops

Ehehehe... Hey, look! It's Dryptosaurus!

-Insert poor excuse here-

Well, exams reared their ugly head, and I wasn't able to update much. Thankfully, it is now summer! And as such I have free time to kill!

Well, long story short, they described something like six new genera of ceratopsians while I was away, including the first of the horned dinosaurs from Europe, as well as the first true ceratopsid from outside North America, and the biggest horns in any dinosaur. The good stuff always happens while I'm away!

Dino Family Spotlight: Coelophysidae

Though most famous for its Triassic record, the coelophysids were a greatly successful group, surviving into the Early Jurassic across North America and Africa. They were light-boned, fleet-footed predators, well-suited to a world of small prey which could run just as fast as it could. They are placed within the Theropoda, and are believed to be more primitive than the ceratosaurs and tetanurans.

Coelophysis bauri was first described by Edward Drinker Cope in 1889 from fossils found in the American Southwest, but it's unsure if these fossils even belong to the dinosaur at all. Later bones attributed to Coelophysis definitely belong to a theropod dinosaur, and as such, Coelophysis is still a valid dinosaurian genus.

Coelophysidae is also home to what is, possibly, the worst dinosaur name ever: Megapnosaurus. Once beloved by dinosaur fans as Syntarsus, the entomologists struck again: Syntarsus was taken by a beetle. In some miscarriage of justice, the entomologists who pointed this out now had the right to rename the animal. It is now Megapnosaurus - "big dead reptile". I'm not sure if this shows a twisted sense of humor on the entomologists' parts, or simply ignorance as to the true nature of dinosaurs.

This family posesses seven species across six genera.

Coelophysidae (Nopsca, 1923)

Coelophysis bauri (Cope, 1889)

Megapnosaurus rhodesiensis (Raath, 1969)

Megapnosaurus kayentakatae (Rowe, 1989)

Camposaurus arizonensis (Hunt et al., 1998)

Podokesaurus holyokensis (Talbot, 1911)

Procompsognathus triassicus (Fraas, 1913)

Segisaurus halli (Camp, 1936)

(Sorry for paragraph-fail. I blame the website!)

Dino Family Spotlight: Herrerasauridae

Herrerasaurids are among the most primitive dinosaurs, and, indeed, are primitive enough to have caused debate in the paleontological community for a couple decades. Though the general concensus is that they are a family of primitive theropods, some scientists hold them to be more basal, belonging to Saurischia incertae sedis.

The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963 in the Ischigualasto Formation of Brazil. The specimen variously jumped around into several different placements, from prosauropods and non-dinosaurian archosaurs, to a primitive carnosaur. Since then, the classification has settled to the two options found in the previous paragraph, and the group is defined as the most inclusive clade containing Herrerasaurus ischigualastensis, but not Passer domesticus.

The family dates to the Late Triassic, from about 228 to 225 million years ago. They are most commonly found in South America (Brazil & Argentina), but specimens are also known from North America (Arizona & Texas). The possibility remains that there could be others found on other continents. The group contains at least three species across at least three genera.

Order Saurischia
Suborder Theropoda
Family Herrerasauridae (Benedetto, 1973)
Herrerasaurus ischigualastensis (Reig, 1963)
Staurikosaurus pricei (Colbert, 1970)
Chindesaurus bryansmalli (Long & Murry, 1995)

Introducing: Dinosaur Family Spotlight!

Normally, in the spirit of the first day of April, I'd come up with something witty. But I'm rather tired today (and looking forward to my spring break!), so instead I'm announcing an upcoming segment on the blog (don't worry, Lizard Watch will be here soon). The Dino Family Spotlight!

For the benefit of those who view my page, I will go through every major grouping of dinosaurs (the families, but in some cases, subfamilies as well), and offer a summary of that group's features, and a list of species which belong in the group. The segment will begin tomorrow with the most primitive of the dinosaur families, Herrerasauridae.

Stay cool!

New Tyrannosauroids and Why I Dislike Ibises (Ibes?)

(Look, there's one now! Curse the little blighter!)

I've been out for a while (Disney World! Whoo!), and as such have not been able to post much on my blog. Two interesting things have happened recently occurred in the world of tyrant paleozoology. The first is a pubis (a hip bone) from a tyrannosauroid found in the Early Cretaceous of Dinosaur Cove, Australia.

This is the very same place where Leaellynasaura and the famous "dwarf allosaur" (now known to be a neovenatorid) were found. The bone is not enough to be considered diagnostic, so I applaud those who described it for not slapping it with a new name. (And I do mean you, Santanaraptor.) This is interesting, as before this find, tyrant dinosaurs are known only from the Laurasian continents of North America, Asia, and Europe. Does this mean that other tyrants might soon be found in India? Madagascar and Africa? South America? Who knows, maybe even Antarctica!

Second is the first tyrant known from Russia, a small tyrannosauroid named Kileskus aristotocus, from the Middle Jurassic of Western Siberia. Russia is notably sparse in dinosaur fossils, though many have been found in the Amur River Valley and in not-too-distant Kazakhstan and Uzbekistan. The animal is known from some premaxillary bones and other cranial elements, and is assumed to be a more basal relative of the Proceratosauridae and others.

And, to the main point of this little post... The American white ibis. Eudocimus albus. While at Disney World's Animal Kingdom, I leaned in to say "Hello!" to one of these small birds, and it snapped at me! Only my expert ninja skills (screaming like a girl and falling over) prevented me from sustaining a bruised nose. I can conclude that the bird was probably startled by the loud noise, and indeed, I'll have to remember not to bother any avians in the future.

Clearly the birds still contain predatory instincts from their dinosaur ancestors, among which are the hunting habits of birds of prey and extinct terror birds. Anyone who doubts me can go to Disney and try being friendly to an ibis.

Linheraptor exquisitus - A New Dromaeosaur!

If you couldn't tell by my user name, dromaeosaurs are my favorite among the dinosaurs. The raptors may not have been as big (or as scaly!) as the Velociraptor of Jurassic Park fame, but they were fast and effective hunters which survived over fifty million years.

So I'm excited about the discovery of yet another new dromaeosaur from the Cretaceous of Inner Mongolia, China, Linheraptor exquisitus. It was described a few days ago by a team including fellow paleo-blogger, David Hone of Archosaur Musings. At two meters long (this is a bit larger than six feet, I believe), it ranks similarly in size to the related Velociraptor. It lived about 75 million years ago in the Maastrichtian. If I had to guess, it is part of the Velociraptorinae, since Tsaagan and Velociraptor seem to be its closest relatives.

The specimen shown at the top is very well preserved, though sadly the tail doesn't seem to be visible in the picture.

Yet Another New Species: Abydosaurus mcintoshi

So far, 2010 is turning out to be quite a good year for dinosaur discovery. Abydosaurus mcintoshi was described this week by Chure et al. from skull and neck material found in Dinosaur National Monument. It dates from the Albian stage of the Early Cretaceous, about 105 million years ago.

Abydosaurus is a brachiosaurid, making it part of a relatively successful family of sauropod dinosaurs. More famous relatives, such as Brachiosaurus and Giraffatitan, are known mostly from the Late Jurassic, though some, such as Sauroposeidon, are also known from the Early Cretaceous. The brachiosaurids are a part of a group of sauropods known as macronarians, for their large nasal cavities (as opposed to those of diplodocoids).

Abydosaurus is notable for its relatively thin, peg-like teeth, which are quite different from those of the earlier Brachiosaurus. There is a marked change from the broad-crowned sauropod teeth of the Jurassic, which seems to have appeared independently among different sauropod groups throughout the Cretaceous. By the Upper Cretaceous, no broad-crown-toothed sauropods are found anywhere in the world.

Plurals in Latin! This is important.

Just to clear a few things up with plurals in Latin (since in paleontology, the language is dealt with often).

If it ends with -us, generally its plural ends with -i. Example: cactus -> cacti. Some other plurals for words, however, end with -era. Example: genus -> genera.

If it ends with -a, its plural ends with -ae. Examples: alumna -> alumnae, aurora -> aurorae.

If it ends in -um, its plural ends with -a. Examples: medium -> media, datum -> data. (Yes, data is plural.)

If it ends with -ix, its plural ends with -ices. Example: appendix -> appendices.

If it ends with -is, its plural ends with -es. Example: parenthesis -> parentheses.

Oddball words like species maintain their singular form in the plural.

I hope this brief guide helped you. The more you know. Because knowledge is power!

Lizard Watch

(Pictured: Eublepharis macularius. Not mine, though.)

Good news, everyone! Within the next few weeks, I will be obtaining my very own squamate, an Eublepharis macularius. Or, in common terms, a leopard gecko.

The Squamata are an order of scaled reptiles, the most recent major group, having found their origins around the lower Jurassic. The order includes not only lizards but snakes, thereby comprising the vast majority of sauropsids (reptiles) alive today. Other orders, including Crocodilia (within the Archosauria; Archosauria also contains birds and dinosaurs), Sphenodontia (tuataras), and Testudines (turtles and tortoises) make up the remainder of reptiles alive today. Of course, Squamata also contained the now-extinct mosasaurs, making my future scaley compadre a not so distant cousin of the great Tylosaurus proriger.

Within suborder Scleroglossa, the infraorder Gekkota, and family Gekkonidae, the leopard gecko originates from the arid scrubs and deserts of southern Asia, throughout Pakistan and India. It is unique among geckos, as it has eyelids. It's a well-established pet in many countries, common as a reptilian pet throughout the United States.

Like other geckos, it posesses over 14,000 hair-like growths called setae (singular: seta) on its feet, which allow it to walk on vertical surfaces without liquid or surface tension. Each of the setae has a diameter of about 5 micrometers, and each is covered with anywhere from 100 to 1000 spatulae, which are 0.2 micrometers in width.

I'm really looking forward to having my very own squamate around the house. However, I can only hope the two local Felis silvestris catus aren't quite as anxious about its arrival.

DinoBlag: Batrachotomus

A more esoteric choice on my part: Batrachotomus kupferzellensis. It is a prestosuchid rauisuchian from the Middle Triassic (Ladnian) of southern Germany. It was found in a swampy region, so it's no accident that its name means "frog cutter".

It grew up to 20 feet (6 meters) long, making it one of the larger of the rauisuchians. Rauisuchians are, of course, a suborder of crurotarsan archosarus, mostly land-bound crocodiles which lived from the Permian until the Triassic. They were very widespread, and have been found on nearly every continent. Batrachotomus is distinguished from its cousins by a series of bony, leaf-shaped scutes on its back known as osteoderms. This term means "bony skin", which is precisely what they were.

With a tall, narrow skull and a relatively upright posture, it is easy to see why Batrachotomus and its ilk ruled the Triassic world. It was well-suited for hunting the prey it needed to, as it was faster than most of them.

It lived in the same habitat as several large amphibians like Mastodonsaurus, nothosaurs, and relatives of the marine Tanystropheus.

DinoBlag: Bistahieversor

(Pictured: The skull of the animal in question.)

I know, right? Two blog posts in a day. Scandal. But hey, if I have the day off, why not?

I kinda missed the media hype a week or so past when this litte guy was discovered in the Kirtland Formation (formerly the Ojo Alamo Formation, after which the contemporary Alamosaurus was named). But now I can put him in a typical DinoBlag: Bistahieversor sealeyi. (Here, I'll help you out: bis-TAH-ee-eh-ver-ser SEEL-ee.)

Our friend Bis (as I will henceforce refer to him/her/it as) was gathered in the 1990s under the dubious name Aublysodon, which was attributed a century ago to the teeth of an unidentified juvenile tyrannosaur. Earlier last decade, it was attributed instead to a new species of Daspletosaurus, but research shows that it was different enough from Das (I'm a lazy typer) to belong to its own genus. And so, this year, Bistahieversor was born.

Its name means "Bistahi destroyer", Bistahi being the location where it was found, and a Navajo word meaning "formation of pueblos". Its adult size is estimated at 30 feet (9 meters), and it lived around 75 million years ago in the lower Maastrichtian. Though its affinities within the Tyrannosauroidea are uncertain, it has a deep snout, not unlike true tyrannosaurids.

Some scientists postulate that it was isolated from the more advanced northern tyrannosaurs by the growing Rocky Mountains, which at the time were far higher than today. By its skull characteristics, in my opinion, I would suppose that the dinosaur fed on hadrosaurs, much like its northern relatives Daspletosaurus, Albertosaurus, and Tyrannosaurus rex.

Bistahieversor sealeyi (Bis will catch on, you just watch!) was described by Carr and Williamson in 2010.

A Look to the Past - The Dinosaur Encyclopedia by Dr. Michael Benton

Dinosaur science has come a long, long way since 1984. Evidence enough of this is a book by Dr. Michael Benton, published that year, which recently resurfaced in my home. Compared with the graceful dinosaurs in Dr. Thomas Holtz's 2004 book with a similar title, the clunky, tripod-like dinosaurs of the older publication are almost comic in appearence.

Not that I blame Dr. Benton, of course. The book is 26 years old. A lot of discoveries have been made, and the book is quite comprehensive for the time. But a look back from over a quarter of a century can be an entertaining experience. A short list of the things said in the book is enough to warrant at least a quiet snicker.

*Tyrannosaurus is the largest carnivore of all time, at 50 feet. (It grew to 43 feet.)
*"Warm-blooded Dinosaurs?" is shown with a skeptical question mark in the index.
*Crocodiles are cited as dinosaurs' closest living relatives. Birds are overlooked.
*Poor Diplodocus is cited as the "most stupid dinosaur", as it has the lowest brain-to-body ratio of any dinosaur. (I don't know if this is still true or not. I'll have to check.

Even the taxonomical differences between then and now are enough to fill this post.

*Tyrannosaurids are Carnosaurs (They're coeulurosaurs.)
*"Anatosaurus", rather than Anatotitan.
*At least it doesn't use "Brontosaurus" as a valid name!
*Oviraptorosaurs are ornithomimosaurs (They're not.)
*All large carnivores, including coelophysoid Dilophosaurus, megalosauroid Megalosaurus and Spinosaurus, and, as mentioned before, tyrannosauroid Tyrannosaurus are apparently Carnosauria.
* Smaller coelophysoids are coelurosaurs (They're not!)
*Therizinosaurus and Deinocheirus are in the Deinocheiridae, which is apparently part of Deinonychosauria. (That's a new one.)
*"Dravidosaurus"
*Elaphrosaurus is an ornithomimosaur (It's a ceratosaur)
*Interestingly, Hypselosaurus is cited as being closely related to Alamosaurus, Saltasaurus, and Titanosaurus, all of which (including Hypselosaurus) would, in 1993, be classed into Titanosauria. (More points for Dr. Benton!)
*It suggests that Mamenchisaurus stood in the middle of ponds and swept around like a vacuum cleaner to eat.
*Noasaurus is claimed to be a deinonychosaur, which would have made it the only of that kind known from South America. Ironically, it wasn't until decades later that unenlagiine dromaeosaurids were found in the same area.
*Pachycephalosaurus is said to be an ornithopod. (It's a cerapod.)
*Though rightfully told to be a saurischian, Segnosaurus is said to be a fish-eater, as this was originally how it was thought to feed. It was, in reality, either herbivorous or omnivorous like other therizinosaurs.
*Spinosaurus is shown as a close relative of Acrocanthosaurus.
*Syntarsus (now Megapnosaurus, or big dead lizard, which is just about the worst dinosaur name ever; no surprise, it wasn't named by actual paleontologists) was one of the first dinosaurs depicted with feathers, but the author approaches this claim with much caution.

But, of course, again, we can't blame Dr. Benton. This was another age (at least in dinosaur science). The book has some very informative parts in the back about the history of the science, as well as the preparation of mounted dinosaur skeletons. And hey. I can assure you, in 2036, paleontologists will be making fun of us for our mistakes. But if we can't laugh at tripods and croc-like bellies, then what can we laugh at?

DinoBlag: Phacops

You heard me. Phacops rana. This is an exciting moment for the blog, as this is the first species featured in a DinoBlag which I actually own a specimen of. Phacops is a classic Devonian trilobite, native not only to North America, but also to Morocco. The specific name is a reference to its eyes, which reminded scientists of the common frog (Rana).

It lived around 400 million years ago in shallow seas, and is a common fossil in many Devonian sediments. It is known for commonly being found in a balled-up position similar to that of the modern pillbug (Armadillidium vulgare). It is the state fossil of Pennsylvania.

Phacops is the state fossil of Pennsylvania, and quite a large trilobite at up to 6 inches in length. Something interesting about its relatives are that they are capable of seeing almost 360 degrees around the animal, which undoubtedly would have allowed it to detect incoming predators.

Tyrannosaurus Species (Also: 50th Post! Whoo!)

(Picture: Which is the tiger? Which is the lion? Where should we draw the line?)

Today, it's easy to tell species apart from one another, even within the same genus (well, generally). We have the luxury of seeing tigers and lions in the flesh, and of seeing their distinguishing characteristics (stripes and manes, respectively). But in paleontology, to the regret of many, things just aren't that simple.

With dinosaurs, we are dealing with something quite different from big cats. These are animals whose living relatives today, crocodiles and birds (you BANDits are in denial!), are very different from their saurian cousins indeed. Of dinosaurs, we have only stripped, petrified bone (except in some very extraordinary and exciting cases, such as mummified Brachylophosaurus and feathered dino-birds from China), which makes it very hard to use characteristics like these to classify them. For examples of living and extinct animals, I will use lions and tigers, and T. rex as my examples for living and extinct animals, respectively.

Any 3-year-old can tell a lion and tiger apart. The lion, Panthera leo, has a magnificent mane and tawny skin. Its legs are relatively well-suited for running, though not as much so as those of the cheetah (Acinonyx jubatus). A tiger, Panthera tigris, is much bulkier than its African cousin, with stouter legs, an orange, striped coat, and a considerable aptitude for swimming. These two animals are so different on the outside, it's hard to imagine clumping them together as the same beast.

But if we take a dip beneath the cats' skin, things become a bit complicated. There are remarkably few anatomical differences between the two, besides the differences in hair and skin, which, one should think, would make the two quite indistinguishable to hypothetical scientists from after the animals in question are long gone. So how can we assume that dinosaurs were any different?

Tyrannosaurus rex is arguably the most famous of all prehistoric creatures. Yet compared to other dinosaurs, it is relatively uncommon. A single species resides within the genus, and has for the century and more that the dinosaur has been known to science. But some scientists insist that tyrannosaurs closely resembling old Rexie are also a part of the genus.

Tarbosaurus bataar is a very close relative of Tyrannosaurus from the Late Cretaceous of Mongolia. There are some small, if appreciable, differences in the skeletons of the two animals, but many paleontologists (palaeontologists?) feel that Tarbosaurus is naught but another species of Tyrannosaurus. Tyrannosaurus bataar would be the name of the dinosaur if it was reclassified. In short, the afforementioned paleontologists want to "clump" Tarbosaurus into Tyrannosaurus.

Some scientists even go so far as to classify Daspletosaurus torosus, considered by some as ancestral to T. rex, as another species of Tyrannosaurus - T. torosus - despite some major differences in skull structure. Where does it end? When does the clumping stop, and poor Das and Tarbo can live in taxonomic peace?

If we can notice these differences in the species even marginally over 70 million years of geologic time, isn't it clear that they were even more different when they were alive? They were probably even more different than lions and tigers (well, maybe not; dinosaurs didn't have hair, after all). If we can't even tell lions and tigers apart in the bone, but can with reptiles which have been extinct for so long, why should these tyrannosaurs be just as closely related?

We frankly don't have the luxury of seeing dinosaurs in the flesh. So who knows? There could have been plenty of Tyrannosaurus species, all as different and distinguishable as tigers and lions. But the thing is, we'll never know, unless some day, we can see the dinosaurs alive. So please: clumpers, please stop clumping! Tarbosaurus and Daspletosaurus are just not Tyrannosaurus.

DinoBlag: Neovenatoridae

One of the more recent developments in the classification of dinosaurs is the 2009 addition of the family Neovenatoridae. The neovenatorids are the last of the allosauroids, relatives of the Jurassic Allosaurus and the Cretaceous giant Giganotosaurus. Neovenatorids range in time from the Early Cretaceous, 128 million years ago, to about 70 million years ago. They are known from South America, Australia, East Asia, and Europe.

Many neovenatorids are characterized by large thumb claws, especially Megaraptor and Australovenator. 7 species across 7 genera are known from this family, placing it in the middle range for diversity among dinosaurs (compare to 9 genera in Tyrannosauridae and 2 in Psittacosauridae).

The type species, Neovenator, is somewhat of an anomaly among the family, being the only species of neovenatorid known outside of the southern regions of the world. It is outclassed only by Aerosteon in size, at 7.5 meters in length. The other species of the family probably averaged somewhere around 4.5 - 5 meters.

Neovenator was described by Martill and Barker in 1996, and the family was described by Benson, Carrano, and Brusatte in 2009.

DinoBlag: Dicraeosauridae

A DinoBlag first: a whole family of dinosaurs. The Dicraeosauridae was a family of diplodocoid sauropods, related to diplodocids such as Diplodocus, Apatosaurus, and Barosaurus. They are, however, distinguished from these dinosaurs by their shorter necks and smaller size. Three species are known of this family thus far: Dicraeosaurus, Amargasaurus, and Brachytrachelopan.

The type species, Dicraeosaurus, was described by Werner Janensch in 1914 for fossils found in the late Jurassic Tendaguru Formation, a fossil formation in Tanzania which also bears Giraffatitan and Kentrosaurus fossils. It is the largest dinosaur in the above diagram, at 41 feet in length. It was named "bifurcated lizard" for the set of small spines on its back.

Another species was not added to the family (named in 1929) until 1991, when the distinctive Amargasaurus was described. It had a set of tall spines running down the length of its neck. At 33 feet, it was smaller than Dicraeosaurus but larger than Brachytrachelopan. It was described by Leonardo Salgado and Jose Bonaparte, from the Cretaceous of Argentina.

The smallest species in this diagram, Brachytrachelopan, was described by Oliver Rauhut et al. in 2005 for fossils also found in Argentina. It had the shortest neck in the family. Indeed, the shortest neck of any sauropod. Its name, "short-necked Pan", in reference to the Greek god of shepherds.

This family was native to the southern continents of Gondwana, and must have migrated here from the northern continents before they broke away from the north, around 140 million years ago, but after the diplodocoids came into existence, 154 million years ago. That is, of course, unless the order Diplodocoidea came into being on the southern continents. Dicraeosauridae is classified either as the most inclusive clade containing Dicraeosaurus but not Diplodocus, or as any diplodocoid more closely related to Dicraeosaurus than Diplodocus.

The diagram at the top was created by Nobu Tamura, and is used here under the GNU Free Documentation License.

And the First Dinosaur of the New Year Is...

(Pictured: Not Texacephale, but its relative Prenocephale)
Texacephale langstoni! This dinosaur was described yesterday from cranial remains found in the Big Bend region of Texas. It has been found to be a relatively pachycephalosaur from the late Campanian in the Cretaceous.

It's helped to rewrite pachycephalosaur taxonomy, too. Classification of this dinosaur has shown that pachycephalosaurs found in Asia, such as Homalocephale and Prenocephale form a monophyletic group. A monophyletic group is determined by whether or not the common ancestor of all members of the group would be considered of that group. For example, the common ancestor of an ostrich and a sparrow would have feathers, wings, and be warm-blooded, and therefore a bird. This means that Aves is a monophyletic group. Whereas the rhino's ancestor is related to horses, an elephant's to seacows, and a hippo's to pigs, which makes the group Pachydermata a non-monophyletic group.

And, surprisingly, analysis of its skull has revived the debate over whether or not pachycephalosaurs could have used their skulls in combat. And here I was, betting on the first dinosaur of 2010 to be yet another theropod.

Happy New Year!

It's 2010! A good new year to whoever may be reading this. Here's hoping that this new decade brings plenty of new dinosaurs into the realm of science, and that maybe, just maybe, we'll see some good dinosaur documentaries (for once)!