Enjoy some Images

Today, enjoy some imagery of Temnodontosaurus. Also, enjoy some toy reviews. The second video is a model from CollectA and is particularly interesting as it includes a pup in the process of being born; it is admittedly a little odd.

Also enjoy this short clip that is said to portray Temnodontosaurus. Because there are not a lot of Temnodontosaurus videos, definitely spend some time checking out this cartoon about Mary Anning as well.

Short on Facts

I always find it to be a little odd when there are few places to find facts on what should otherwise be a fairly well-known animal. Considering Temnodontosaurus' place in fossil finding history and its giant eyes, it ought to be a little bit more well-known online. However, aside from a few tribute videos and some animation tests, there are almost no videos online. There are also fewer fact pages than we would normally expect for such an important fossil animal. There is a short encyclopedia entry on KidzSearch (a site we have not used lately) and a very slightly longer entry on the Ancient Animals Wiki. A more informative source of information that includes a slightly more in depth article and a list of facts can be found on Prehistoric Wildlife, a site we have found useful to learn from for a long time around here.

Celebrating Lyme Regis

©Dmitry Bogdanov

The holotype of Temnodontosaurus platyodon (originally Ichthyosaurus platyodon) is approximately 6.1 m (20 ft) long and was discovered in 1821. Although the name means "cutting tooth lizard" the fossil is best known for two radically different reasons. The first is that the orbits and the 25 cm diameter sclerotic rings indicate that the eyes were approximately 20 cm (8 in) in diameter, making these the second largest known eyes in any animal. Prior to a 2008 dissection of a rare Colossal Squid (Mesonychoteuthis hamiltoni) which has eyes approximately 27 cm (11 in) in diameter Temnodontosaurus had the largest known eyes. The second most important reason that Temnodontosaurus is well remembered is because this large ichthyosaur was one of the first fossils found by Joseph and Mary Anning in 1811; it was initially described as a crocodile. Joseph outlived Mary by a few years, but Mary was the true force in the family fossil collecting business despite being largely deleted from the literature of the time by the geologists to whom she sold her fossils. Anning also led geologists (including Buckland, Agassiz, Owen, and Conybeare among others) on expeditions, taught them how to collect fossils from Lyme Regis, and trained their field assistants and wives how to collect fossils. Temnodontosaurus may be well known for being discovered by the Annings, having large eyes, and being one of the first known ichthyosaurs, but it is not the best known of Anning's discoveries; that distinction belongs to (depending on who one asks) either her 1823 discovery of Plesiosaurus, or her 1828 discovery of what later became known as Dimorphodon. During this week we will talk a little about Temnodontosaurus and Mary Anning both every day. The reason for that, for those interested, is that many of Anning's discoveries were made or published during December and her life was actually strangely influenced by the month. Additionally, it was recently announced (14 December) that a movie based on part of her life, titled "Ammonite" will begin production in March 2019. Anning and December seem intertwined and Temnodontosaurus was her first big find. It all goes together for a fitting end to the year.

Also, I just realized this is blog post #2500. Hooray!

Videos of Giant Sauropods

Invest a little time in learning a little bit about Sauroposeidon today with WizScience and Dinosaurs Unearthed:

The Tallest Sauropod

Sauropods were enormous animals, for the most part. They certainly have a wide range of sizes, but the absolute largest sauropod ever known was discovered in southeast Oklahoma and described in 2000 by Wedel, Cifelli, and Sanders. Trace fossils, in this case footprints, from Oklahoma, Wyoming, and Texas have long been associated with the animal as well and, despite the holotype consisting of only a few cervical vertebrae, many more bonebeds and isolated fossils have been discovered in these states since 2000. Named the "lizard earthquake god" that was "perfect before the end" Sauroposeidon proteles was estimated to have possessed a neck approximately 11.25–12 m (37–39 ft) long based on the largest cervical vertebra of a sauropod known, which measured in at 1.4 m (4.6 ft) long. That is a fairly large singular bone; almost as tall as my mother actually! It also makes the neck about 2 m (7 ft) longer than the next longest sauropod neck (belonging to Giraffatitan).

CC BY-SA 3.0 Stephen O'Connor

It's in the Name

It was mentioned earlier this week that Protarchaeopteryx, as a name, translates literally to "Before Archaeopteryx". This poses a small problem because Protarchaeopteryx is a Cretaceous archaeopterygian and Archaeopteryx itself is a Jurassic animal. Geologically speaking, Archaeopteryx predates Protarchaeopteryx by approximately 25MY; though it is important to note that the accepted span of existence for Archaeopteryx is 150MYA - 125.45MYA and Protarchaeopteryx shows up in the fossil record at 124.6MYA. This means that they are not, temporally, that distant from one another. This does not necessarily reflect their phylogenetic relationship to one another. Now, the reason that we brought up the names is that the implication of the name is not actually what the name means. What I mean, and what Ji and Ji meant by that in 1997, is that Protarchaeopteryx did not come before Archaeopteryx, but rather it possess characters which appear to place it in a phylogenetically primitive position in relation to Archaeopteryx. The justification for the name as assigned by Ji and Ji was that "...it [Protarchaeopteryx] is regarded as more primitive because it has a more elongated tail, more robust pelvic girdle, longer and larger hind limb, and unfused proximal metatarsals [than Archaeopteryx]." These characters, it may not require stipulating, are more derived in Archaeopteryx. To better understand the description and read the translated version of that 1997 paper, please see the reference presented below.

Reference:
Ji, Qiang, Shu’an Ji, and Translated By Will Downs. "A Chinese archaeopterygian, Protarchaeopteryx gen. nov." Geol Sci Tech 238 (1997): 38-41.

Caveats of the Internet

Any time that one searches for anything discussing birds, dinosaurs, and/or evolution, one must be aware of the confusing and argumentative cyclone of websites that are out there. Looking up an animal like Protarchaeopteryx is a part of that rule and certainly not an exception. A safe place to start is something like the WizScience video below that just presents facts that we know about this dinosaur without adding conjecture or argument to what is presented.

Of course, we cannot assume that all of the videos and websites are as neutral as those put forth by a group like the team behind WizScience. That being said, there are websites that do avoid the arguments on the internet by presenting information (and being fairly regularly updated to maintain that information) without allowing comments; it really can be as scary as I am making this sound when a website discusses the dinosaur-bird transition and key fossils and allows for commenting. Pages that are safe include:
Encyclopedia Britannica
The Natural History Museum of London
Age of Dinosaurs
Dinosaur Jungle
Enchanted Learning

Early Feathers

We always love a fossil that we haven't talked about or a fossil that has had a lengthy absence and we are talking about it for the first time in a really long time. This may or may not be one of those times; I feel like we have covered Protarchaeopteryx robusta before, but searches of the entries on the blog turned up nothing. That is almost 8 years worth of entries to search though, and considering that with this year as an exception of every day entries, that is a search of almost 2500 entries. Regardless, the small "Before Archaeopteryx" feathered theropod is an interesting dinosaur that was discovered in the Yixian Formation of China in rocks that belong to the Aptian age of the Early Cretaceous (approximately 124.6 MYA). There are questions about the validity of the animal; some discussion has involved its relationship to another small dinosaur, Incisivosaurus (we may visit this animal next week to follow up). However, with that relationship in question and not cemented or ignored, another relationship is still alternatively proposed for Protarchaeopteryx; that this animal represents a basal oviraptorosaurid. Despite this ancestral mystery, we do have some idea about what the animal ate (likely mostly herbivorous but sometimes supplementing this diet with meat) and what it was covered in (symmetrical, flightless feathers) and we can therefore form a few hypotheses about the way that Protarchaeopteryx lived in and interacted with its environment and other animals.

Protarchaeopteryx holotype at the Geological Museum of China
CC BY-SA 4.0

Two papers

There are two important papers that everyone interested in Rubeosaurus should take a moment to read today. These papers discuss, first, some interesting remains of "Styracosaurus" ovatus in which the authors, McDonald and Horner, introduce new remains attributed to this species and then analyze the characters and describe the phylogeny of the animal. This paper contains the naming of the new genus, Rubeosaurus, based on this material and is therefore important in knowing where the dinosaur came from and what was known about it previous to its naming in a new genus in 2010. The second paper is about a subadult specimen of the genus that was discovered somewhat recently and described by McDonald in 2017. This description is actually a revisiting of a previous description of another dinosaur (Brachyceratops) and places a young animal within the genus Rubeosaurus. Additionally, this description causes the name Brachyceratops to be considered invalid, or as we more commonly say in paleontology, it is a nomen dubium (a problem name).

It Refers to Brambles

One might imagine that with a name like Rubeosaurus ovatus the person naming the dinosaur may have been poking fun at someone, but the name actually means "Bramble lizard" and references the appearance of the ceratopsian frill that makes up a good portion of the known skeletal elements. Originally named by Charles W. Gilmore in 1930 as a species of Styracosaurus, Rubeosaurus was split from that genus in 2010 by McDonald and Horner following a phylogenetic analysis conducted using new material attributed to what would be renamed Rubeosaurus. The ceratopsian dinosaur has a similar frill to its close relatives Styracosaurus and Einiosaurus. These frills all possess large parietal fenestrations and are bordered by large conical processes surrounding these cranial bones and highly ornamenting the skull. A singular and immense nasal horn is also present in Rubeosaurus, just as in its close relatives.

©Lukas Panzarin CC BY 2.5
From McDonald and Horner 2011

Papers of Many Measures

There are many Dimetrodon papers. A significant number of those papers are descriptions of different finds of Dimetrodon from various different places. The original naming papers would be most interesting, if we had them somewhere online. We do not, to my knowledge. However, we do have the first Dimetrodon species known from Europe, the first from outside of North America actually, which was found in the Bromacker assemblage. This is a Lower Permian formation in and around the Thuringian Forest of Central Germany.

There are other descriptions of Dimetrodon as well. Some of these regard the jaw muscles of the interestingly shaped skull of Dimetrodon. Other venture into describing how Dimetrodon may have regulated its temperature using its unique sail structure. The structure of the sail is, of course, a constant subject of study. Like any other body part, the sail could be subjected to injury as well, and studies have certainly been conducted that on said injuries.

Many of these studies together have led to phylogenetic studies of Dimetrodon. The pelycosaurs, in general, are in an interesting position in the evolutionary tree of synapsids. One of the papers I enjoyed reading when I first learned systematics and began dealing with trees is this paper by Ken Angielczyk which uses Dimetrodon as an example species in how to think about trees (otherwise discussed as "tree thinking") how to use them to understand relationships between taxa.

Not A Dinosaur

Pelycosaurs are not dinosaurs. As Dimetrodon is a pelycosaur, Dimetrodon is also not a dinosaur. This has mostly been eroded from the popular psyche, though there are still vestiges of Dimetrodon's inclusion in the world of dinosaurs out in the modern world. These videos will make sure that everyone knows what a Dimetrodon is and is not.

Emily Graslie (she is a professional science communicator, so expect a well delivered video) on Brain Scoop:

A top ten list of facts. This video again addresses the fact that Dimetrodon was not a dinosaur straight off the bat. It then lists some interesting facts about Dimetrodon. The video includes a lot of images and video game animations.

New Old Animals

Sphenacodontids ("Wedge point tooth") are a group of synapsids that are known from fossils found across Europe and North America from ages between from the Late Pennsylvanian to the Middle Permian. The most well-known examples of not only sphenacodontids but also pelycosaurs is the large headed apex predator known from Texas and Oklahoma (mostly), Dimetrodon ("Two measures of teeth"). The genus Dimetrodon actually consists of 13 recognized valid species; though we regularly hear Dimetrodon referenced as though it is a single species (generally the type species, D. limbatus Cope 1877). The general description of Dimetrodon species is a group of animals presenting with tall laterally compressed skulls, a large dorsal sail, and a tail composed of upwards of 50 caudal vertebrae, accounting for a significant portion of the total length of the animals. The sail is what most people think of when they think of Dimetrodon, but these pelycosaurs are actually named after their teeth, which consist of 1 - 2 pairs of large caniniform teeth and large incisors in the front of the mouth and smaller teeth caudally. Also intriguing in the skulls of Dimetrodon species are primitive nasal turbinates, appearing to indicate a capability of warming and cooling air as it was inhaled and exhaled and what appears to be a transitional morphology of the ear that would give rise to the mammalian ear. The story of the mammalian ear is far more complicated than the previous sentence makes it sound, but this intermediate ear morphology is important in overall ear evolution.

There are many reasons that Dimetrodon is an interesting animal to study and, given time this week, we can get into some of the studies that have been done with disparate species of the Dimetrodon genus. Dimetrodon will always stand out because of their importance in the evolutionary history of synapsids, their unique morphology, and, personally, because the first model I ever built was of a Dimetrodon standing on a rock. It is very possible that this was the model kit (I was young and it was forever ago, but this brings up the memory of building it).

 Also, here is a nice illustration of a few of the species of Dimetrodon scaled to one another by Dmitry Bogdanov.

©Dmitry Bogdanov

Too Many Choices

Probably because Simosuchus has such an interesting skull and teeth for a crocodilian relative there are a number of papers and studies of Simosuchus. The odd shape and the intriguing phylogenetic position of Simosuchus are also often studied topics as well. I know that a number of the readers here have read a lot of these papers, and maybe even know them by heart. The discussions here lately have been quite vibrant and I hope they continue, so if anyone reads these papers and has questions please feel free to ask them. I am sure someone can answer them. Instead of describing each paper and then linking them, I am simply going to link them by subject here. As a fair warning, many of these papers come from a 2010 Memoir edition of the Journal of Vertebrate Paleontology specifically about Simosuchus (read as you may need to look for additional links to read these):

Description paper by Buckley et al (2000)

Phylogeny of Simosuchus by Turner and Sertich (2010)

Craniofacial morphology by Kley et al (2010)

Postcranial skeleton:
Appendicular by Sertich and Groenke (2010)
Axial skeleton by Georgi and Krause (2010)

Osteoderms by Hill (2010)

Well Done Videos

Probably not the group that we would normally turn to here to get facts and videos, the Expeditioner's Discovery Guild is a channel on YouTube that has a lot of wide-ranging videos. One of their videos is the 7:21 second description and artwork compilation addressing Simosuchus. There is a lot of good information here and it is worth watching. It actually directly answers some of questions that people have asked in the last 24 hours as well.

Pug-o-dile

The pug nosed crocodile, Simosuchus clarki (Buckley et al. 2000) is named for its short and blunt snout. Recovered from the Mahajanga Province of Madagascar, the small (2.5 ft; 0.75 m) crocodylomorph had small leaf shaped teeth and is thought to have been one of a number of early suchians that was actually herbivorous rather than carnivorous. There are quite a few interesting facts about this suchian and its lifestyle that tell us a lot about the evolution of crocodiles. Stick with us to see tomorrow what kinds of interesting facts we will share tomorrow.

Photo of ROM display specimen by D. Gordon E. Robertson

Pseudosuchian Archosaurs

Rather than spend today telling the intrepid readers (and viewers of videos) what a pseudosuchian is and is not, I present to you today videos that show, describe, and discuss Revueltosaurus.The genus Revueltosaurus consists of three recognized species: R. callenderi Hunt, 1989 type; R. olseni Hunt and Lucas, 1994; R. hunti Heckert, 2002. The first video comes from Petrified Forest and the National Park Service. It describes the finds at the park and where some of those bones come from on the skull of this crocodile relative. The second video features NMMNH Chief Scientist Spencer Lucas talking about what exactly Revueltosaurus is and is not, in a very short manner of time (the clip lasts approximately 90 seconds).

Daspletosaurus Appears on Television

Daspletosaurus was an interesting tyrannosaurid for a number of reasons. One of the reasons that has been explored was that Daspletosaurus was contemporaneous with another tyrannosaurid, Gorgosaurus libratus. The BBC show Planet Dinosaur was willing to imagine the world in which these two gargantuan dinosaurs lived, how Daspletosaurus may have hunted its prey, and how Daspletosaurus and Gorgosaurus may have interacted. The clip below only shows Daspletosaurus hunting and fighting with a Centrosaurus however.

Facts and Cartoons

I'm A Dinosaur did a little bit less packing in of the facts on Daspletosaurus than they typically do, however it is still entertaining and has some facts for everyone.

The facts are well represented today though. If one chooses to read, you could visit ThoughtCo, the BBC, and even Enchanted Learning (if you want a very quick sheet of facts that are kid-friendly). A more in depth discussion of facts is also available in the I Know Dino podcast's Dino of the Day. This is available on YouTube:

The Frightful Lizard

The "Frightful Lizard", Daspletosaurus consists of two recognized species: D. torosus Russell 1970 and D. horneri Carr et al. 2017. Daspletosaurus was at the top of its game during the Late  Cretaceous approximately 77 to 74 million years ago. Fossils of Daspletosaurus have been found in Alberta (D. torosus) and Montana (D. horneri) and are contemporaneous with Gorgosaurus, Centrasaurus, Hypacrosaurus, Brachylophosaurus, and Albertaceratops, among others. It is hypothesized that Gorgosaurus and Daspletosaurus may not have been in direct competition as apex predators, allowing for some niche partitioning that enabled them to live in the same areas at the same time without out-competing one another. As the more robust of the two genera, Daspletosaurus may have been more likely to prey on the more physically robust and difficult to take down ceratopsians than hadrosaurs; leaving hadrosaurs for lean times and Gorgosaurus.

©Dmitry Bogdanov

Different -aroo

The kangaroos now exists as two species in one genus in Australia (and outside too as zoo animals and, increasingly, as pets). However, like any living animal, the kangaroos have ancestors, and a lot of them were very interesting. There have been kangaroos that walked instead of hopping and there have been kangaroos with rather large fangs. Most of those kangaroo ancestors have a -roo ending, which makes for some interesting names as well. One of the newest of these animals is the first true kangaroo known from 23 million years ago. This kangaroo, Cookeroo (divided into two species: C. bulwidarri and C. hortusensis), is also thought to have walked and scurried rather than hopped across the Australian landscape. These hypotheses are based mainly off of phylogenetic position (based on what I have found), as the paper describing the fossils describes numerous skulls, which are mostly incomplete, though some are fairly complete.

Holotype of Cookeroo bulwidarriPhoto posted by Dr. Kaylene Butler

I Forgot Yesterday

Yesterday I had a video with Jeffrey Wilson all lined up and then I forgot to post it. So therefore, here today is Dr. Wilson talking about the large sauropod eating snake Sanajeh. He is seated next to a sculpture of the fossil which, in my opinion, is pretty fantastic. The fact that the fossil itself depicted this scene is one of the fascinating things about paleontology. Not only do we sometimes find new animals in fossil deposits, but sometimes, such as with Sanajeh, we get to see a scene of nature's beauty and ferocity frozen in time forever. Enjoy the video:

Dinosaur Train Facts

Dinosaur Train delivered facts are always a nice short video full of facts that we can rely on. If that video is not enough there is also the ThoughtCo fact page.

Snakes and Fossils

In 2010 Jeffrey Wilson and colleagues described a fossil snake found in the Western Indian state of Gujarat outside the village of Dholi Dungri. That snake is known as "Ancient Gape" or, in Sanskrit, Sanajeh indicus (indicus coming from the Latin meaning from India). The snake was discovered coiled around sauropod eggs, with an additional 50 cm long sauropod body found nearby. This Late Cretaceous snake, a Madtsoiid or Gondwanan clade snake, is thought to have regularly preyed on sauropods because of this discovery. Vertebrae, ribs, and a very rare but very fortunate nearly complete cranium including the lower jaw were discovered in this fossil. In extant snakes the head is extremely loosely connected together, as it was in Sanajeh. Even now these modern snakes are rarely found intact because of these loose connections. The fact that Sanajeh was discovered with a nearly complete skull and jaws is remarkable, and, as we can see in the line drawing of the fossil, uncovering this find must have been fairly fantastic.

From Wilson et al., 2010

Imagery

The majority of posts lately have been the kind of posts I can do with minimal research, you may have noticed. This is because I am doing a lot more work in my personal life and career than I had been doing previously. That sounds like I was lazy before, but that's not what I intended. At any rate, you can continue to expect a number of posts a week still, which is why we all visit the page to begin with. Today, for example, the simple posting you see here is one of the more interesting images of this small ornithischian ball of feathers. All of the artistic impressions of Kulindadromeus appear to have taken the feathering to an extreme such that the dinosaur looks less like a dinosaur than it does a small chicken or duck chick. My favorite version of these fluffy versions of Kulindadromeus is Jed Taylor's watercolor-esque duo which he posted on Twitter. These two are less fluffed than other versions and there is a somewhat abrupt appearing end of the feathers at the base of the tail. If you have a favorite share them in the comments below.

©Jed Taylor

More Popular Movies

Yesterday I posted some fact videos. Today, there are some informational videos that tell you about reconstructing the dinosaur and the feather structures that were discovered in the fossil material.

A Runner in Motion

On this beautiful, but very hot, Sunday, watch some nice fact videos and a slideshow of scientific illustrations of Kulindadromeus. Do not let my short entry here belittle the facts on these videos:

I Know Dino:

WizScience:

"Tribute" video:

All Feathered

Kulindadromeus zabaikalicus (Runner of Kulinda + the Russian subject of Zabaykalsky Krai) was a Jurassic ornithischian, an herbivore, and was found in Russia and described in 2014 by Godefroit et al. These are all rather uninteresting facts; however, Kulindadromeus is a very important dinosaur. This dinosaur was discovered with traces of its integument evident with the fossil. That integument is consistent with the structure of protofeathers that have been discovered in a number of Coelurosaurian dinosaurs, early birds, and dromaeosaurs. The discovery of feathers in a non-avian line dinosaur indicates that the protofeather may have been a characteristic that was basal to all dinosaurs and not just the dinosaur family tree that eventually took flight.

©Nobu Tamura

Living Relatives

The Chacoan peccary (Catagonus wagneri) of Paraguay, Bolivia, and Argentina numbers approximately 3,000 animals remaining in the wild. This is important for a number of reasons, but the most important reason for us today is that, as the closest remaining descendant (hypothesized) of Platygonus, it is a stand in for our fossil peccary. Though smaller than its extinct ancestor genus Platygonus, Catagonus shares an interesting part of its known history with Platygonus. The Chacoan peccary was initially described as an extinct animal of South American in 1930. It was not until 1971 that living examples of the peccary were found by non-native scientists. The native people of Argentina showed the animals, which they called tagua, to biologists that were in the area. This video shows images of the tagua or Chacoan peccary, which stands in for its ancestor Platygonus.

New Week

I intended to discuss the book Unnatural Selection more than I was able to last week, but I received an email that has kept me fairly bust since last Monday or Tuesday. Instead of spending multiple weeks on the book, I thought that this week we could di○scuss a fossil ancestor of one of the animals that is highly important to discussions in the book about selective breeding. We have discussed the origins of cats and dogs a number of times here and we have also discussed more than a few early birds, their cousins, and their ancestors. The remaining group that I had mentioned from the book is that lovable farm (and table group), the pigs (a magical animal, as regards the table comment).

Suidae consists of a large group of animals, both domesticated and feral, today. At one point we tried to discuss the origin of pigs, but they are a diverse group of animals that have evolved into 17 species across 6 genera and a wide variety of sizes and diets. Also, it was a two entry week, because I was extremely busy, in which we discussed Strozzi's Pig (Sus strozzi). The story of the evolution of the domesticated pig begins with the wild boar (Sus scrofa) and Strozzi's pig is a step along the road between ancient relative and modern pigs. Part of the reason Strozzi's pig died out is actually tied to surges in the population of S. scrofa. Going farther back on the family tree is somewhat problematic, but entertaining because the clade that all pigs and boars belong to is called Artiofabula which welcomes its own puns. Despite all we know about living pigs and boars and having a general idea about their familial relationships, there is not that much known about the origins of Suiidae itself. However, because we had a brief discussion about S. scrofa and domestication before, we are going to talk this week about an ancestor of the peccaries, rather than the wild boar.

Peccaries of the family Tayassuidae in the group of Suidae are the only pigs native to the Americas. Historically measuring approximately 90 and 130 cm (3.0 and 4.3 ft) in length and about 20 to 40 kg (44 to 88 lb), peccaries are smaller than boars and domesticated pigs. Wild pigs and boars in the United States, for instance, are not peccaries but feral versions of the domesticated pigs that came over with European settlers. One of the most well-known wild suids in the United States, the javelina, is a peccary though. Confusion between feral domesticated pigs and peccaries is very common. Regardless, peccaries have their own rich history in North America. One of the extinct members of the family, Platygonus, consists of 18 described species of ranging from Canada to Mexico and California to Pennsylvania throughout the Pliocene and into the Pleistocene. Platygonus was rather large for a peccary at 1 m (3.3 ft) long. Long legs made it capable of running at a fair speed and tusks allowed it to defend itself from predators. It is thought that these peccaries lived in herds as well, making them a bit more well protected than solitary pig and peccary species.

©Charles R. Knight, Platygonus leptorhinus

Classy Introductions

In order to name something, you need to be able to define the parameters of that thing — to know categorically when it ceases to be one thing and becomes another.

- Page 8, Unnatural Selection 

Every science text that aims to cross over to popular nonfiction work needs to have a very good introduction that not only grabs the reader's attention but also explains the basic tenets of the book's context in a way in which non-scientist readers can follow along and apply the fundamentals of these ideas. Application can be either within the text or outside of the book. Most authors that care about teaching their audience (we hope all authors, of course) spend a great deal of time explaining these basic principles of their text to make this process easier. The first few chapters of Unnatural Selection outline some of the basic principles of evolutionary science including basic lessons in phylogenetics, speciation, and a basic understanding of plasticity.

I did not mention this yesterday, however, Unnatural Selection is a book that focuses primarily on the phenomenon of dometication in its various forms, that is from the development of livestock to pigeon fanciering and from dog breeding to the very complex nature of swine domestication and hybridization. To sum it up more succinctly, the book is about selective breeding, and the basic principles of how we name animals, how they are related, and how this breeding process has worked over time are very important to understanding the later chapters of the book. Therefore, the first section of the book, in which these principles are taught to the reader, are very important. They are, fortunately, very well written.

As an example, the sometimes difficult to explain concept of organismal plasticity is written such that it is fairly easy to follow as well. In the scope of the book (that is in its use in describing selective breeding), a slightly different definition is used than that of the strict biological definition of the word. In that strict biological sense of the word we are looking at a phenotypic plasticity or the adaptability of an organism to changes in its environment. Unnatural Selection approaches plasticity in terms of the potential for changes over generations, rather than in a single generation. We could say the difference is that between an animal that experiences an environmental change over its life (for a myriad list of reasons hypothetical or otherwise) compared to the changes of a dog (cat, pig, pigeon, parakeet) breed over successive generations (see below for change over time in Bullterrier skulls). That breed can change in many different ways for a variety of reasons including, as van Grouw says, "fashions might simply change." Additionally, because these animals are all interbreeding subspecies, those plastic changes can flip, flop, and twist in amazingly interesting ways over the years because of the breeding of mutts and mixes of purebreeds that become fashionable (think of things like Labradoodles).

©Katrina van Grouw

Skeletons and Popular Literature

A few years ago a book was written called The Unfeathered Bird that was focused on the anatomy of birds, showing birds as they are not often seen in popular literature. The illustrations for the book were hand-drawn skeletal, muscle, and even some feathered images of a wide array of birds, highlighting differences and similarities across a wide range of birds; hitting every bird in this manner would be a life's work and well beyond the scope of a single book. A follow-up work by the author and illustrator Katrina van Grouw was recently published titled Unnatural Selection. Though not a follow-up in the sense of focusing on birds, Unnatural Selection does continue as an investigation of evolution, anatomy, and high quality illustration of a wide range of animals. Over the next week I am going to go over some of the chapters of the book. We will also get to see some of the illustrations that grace the pages of the book.

We can get back to fossil animals next week.

Fame and Mice

As we have stated this week, Mussaurus is well-known among paleontologists and it is actually fairly well-known by the public as well. This is partly because of its bogus claim of being the smallest dinosaur; granted it was the smallest known dinosaur when originally discovered and the hatchlings and juveniles are still quite small for dinosaurs. The sheer number of websites with information, images, and videos of Mussaurus attests to the dinosaur's popularity. If that was not enough, there is also an electronic toy version of the dinosaur and, back after not seeing one of these information trading cards in a long time, Mussaurus is featured below, looking very angry for some reason.

Anatomy of A Mouse Lizard

The first article that appears in a Google Scholar search for Mussaurus is Pol and Powell's 2011 paper Skull anatomy of Mussaurus patagonicus (Dinosauria: Sauropodomorpha) from the Late Triassic of Patagonia. Starting off with the cranium is the right way to go (my research is concerned with the skull, in case anyone wasn't aware). Because there are so many specimens of Mussaurus known to us, there is a lot of the skeleton that is known as well; the head is just the beginning. In fact, Pol also helped to describe some of the postcranial anatomy as well (Otero and Pol, 2013). Like Pol, Mussaurus is known from Argentina, which partially explains why he has been involved in numerous papers on the small dinosaur including Cerda et al., 2014a, Cerda et al., 2014b, and Otero et al., 2017 in addition to the two mentioned above. These studies are all largely descriptions of anatomy, generally either skeletal or joint related. This is not the limit of studies on Mussaurus of course.

Mussaurus had its own profile in the 1993 book Age of Dinosaurs by Peter Dodson which briefly discussed all the details that were known of small dinosaur at that point. Many studies not describing skeletal or joint attributes directly have also been published on Mussaurus that rely heavily on those descriptions, a prime example being Montague, 2006 which generated estimates of body size for over 600 dinosaur species, including Mussaurus. Phylogenetic analyses have been conducted using these descriptions and anatomical characters also; see Upchurch et al., 2007. Lastly, we know that the nests have been described, notably in Bonaparte and Vince, 1979, the paper initially describing Mussaurus from juvenile and infant specimens found in the nest that forms the basis of the title and bulk of the paper. This occurrence of the first Triassic nest on record is significant beyond just the naming of Mussaurus of course. Dinosaur eggs have been known since at least 1923 when the American Museum of Natural History led expedition of Mongolia discovered supposed Protoceratops nests; these led to the naming of Oviraptor and eventually it was discovered that the nest belonged to Oviraptor rather than Protoceratops (another story for another day). This nest, that of Mussaurus, is one of the earliest known dinosaur nests and an important link in the story of dinosaur evolution. Also we can all agree that dinosaur nests are pretty cool and that the earliest dinosaur nests and their tiny occupants are also very cool.

References:

Bonaparte, J.F. and Martin, V., 1979. El hallazgo del primer nido de dinosaurios triasicos,(Saurischia, Prosauropoda), Triásico superior de Patagonia, Argentina. Ameghiniana, 16(1-2), pp.173-182.

 

Cerda, I.A., Chinsamy, A. and Pol, D., 2014a. Unusual endosteally formed bone tissue in a Patagonian basal sauropodomorph dinosaur. The Anatomical Record, 297(8), pp.1385-1391.

 

Cerda, I.A., Pol, D. and Chinsamy, A., 2014b. Osteohistological insight into the early stages of growth in Mussaurus patagonicus (Dinosauria, Sauropodomorpha). Historical Biology, 26(1), pp.110-121.

 

Dodson, P., 1993. Age of Dinosaurs. Publications International Limited.

 

Montague, J.R., 2006. Estimates of Body Size and Geological Time of Origin for 612 Dinosaur Genera (Saurischia, Ornithischia). Florida Scientist, pp.243-257.

 

Otero, A., Allen, V., Pol, D. and Hutchinson, J.R., 2017. Forelimb muscle and joint actions in Archosauria: insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha). PeerJ, 5, p.e3976.

 

Otero, A. and Pol, D., 2013. Postcranial anatomy and phylogenetic relationships of Mussaurus patagonicus (Dinosauria, Sauropodomorpha). Journal of Vertebrate Paleontology, 33(5), pp.1138-1168.

 

Pol, D. and Powell, J.E., 2007. Skull anatomy of Mussaurus patagonicus (Dinosauria: Sauropodomorpha) from the Late Triassic of Patagonia. Historical Biology, 19(1), pp.125-144.

 

Upchurch, P., Barrett, P.M. and Galton, P.M., 2007. A phylogenetic analysis of basal sauropodomorph relationships: implications for the origin of sauropod dinosaurs. Special Papers in Palaeontology, 77, p.57.

 

Mouse Movement

Mussaurus is not a movie star, despite it being a recognizable dinosaur for many people in and out of the paleontological profession. It has been studied and a video showing its range of movement has been posted online by John Hutchinson, author of What's in John's Freezer? and well known locomotion expert known for studying a wide range of animals, fossil and extant, among other topics (see his biographical blurb on his faculty website). Tomorrow there will be a lot more to read than there is to watch today; so do not feel like the mighty Mussaurus is under-represented yet!

Cute Titles

Mussaurus lends itself to cute titles on webpages. One such page, from Mental Floss, is title 10 Mousey Facts about Mussaurus. The facts on this site address issues like the size of the animal and the misinterpretation of the remains as well as other issues in a serious manner; not at all what one expects from a cute website title. These facts are again summarized in a WizScience video, for folks without the time to read websites right now. However, if websites are your Sunday morning or afternoon reading material, there are far more than just the Mental Floss page shared above. There are also pages on Mussaurus on Enchanted Learning, KidsDinos, Prehistoric Wildlife, and a number of other pages (though this may be enough Mussaurus for most people in a day!).

The Mouse Lizard

Reaching an estimated 3 m (10 ft) in length and 70 kg (150 lbs) in weight, the early sauropodomorph Mussaurus patagonicus was an aptly named dinosaur. The name means "Mouse Lizard" and was applied originally to the skeletons of infants, which are considerably smaller at 20 to 37 centimeters (7.9 to 14.6 in) long, because these were the only specimens known for a fairly long time. Some of the first adult specimens were found alongside or within nests of the already known juvenile and infant dinosaurs. Eggs of this species have also been found in some of these nests. The original juvenile specimens were described in 1979 and the first adult specimens were not described until 2013. The first adult specimens in this description were actually reassigned from Plateosaurus specimens that were described mistakenly in 1980. Their similarities make sense because both were early dinosaurs and both were early sauropodomorphs.

©Henrique Paes

Known but not Famous

I mentioned on Tuesday that Staurikosaurus is a much published and important dinosaur in the scientific community. Outside of the scientific community the knowledge about, and reaction to, the existence of Staurikosaurus is minimal at best. Staurikosaurus does appear in a number of popular arenas, including the The Lost World: Jurassic Park video game on the original PlayStation (see the video below at 5:39 for this version of Staurikosaurus). One place we know that people know about Staurikosaurus for sure is Brazil, where the animal was originally discovered and unearthed. Canela, a town near the discovery site, has a statue of Staurikosaurus alongside a small rhynchosaur.

Photo by Sergio Kaminski, CC BY-SA 3.0

Papers and Beyond

Staurikosaurus headlines a chapter in an older edition of the book The Dinosauria. This chapter has been replaced in newer editions of the book, but the importance of Staurikosaurus and the many papers discussing the anatomy and the phylogeny of Staurikosaurus remain in the newly re-designated chapters. These include the papers that initially described the holotype fossil (Colbert 1970) and estimates of missing elements of the skeleton (Grillo and Azevedo, 2011b) as well as those that ask questions about the origin of saurischian dinosaurs and Staurikosaurus' placement in this discussion (e.g. Galton, 2000). Staurikosaurus continues to be studied beyond the skeleton and its phylogenetic importance to the evolution of dinosaurs also. Grillo and Azevedo (2011a) studied the pelvis and hindlimb to describe the state of the musculature in these areas. These papers should be plenty for a day's reading, so enjoy learning more about the anatomy of Staurikosaurus and where this dinosaur sits in the dinosaur family tree!

References:
Colbert, E.H., Price, L.I. and White, T.E., 1970. A saurischian dinosaur from the Triassic of Brazil. American Museum novitates; no. 2405.

Galton, P.M., 2000. Are Spondylosoma and Staurikosaurus (Santa Maria Formation, Middle-Upper Triassic, Brazil) the oldest saurischian dinosaurs?. PalZ, 74(3), pp.393-423.

 

Bittencourt, J.D.S. and Kellner, A.W.A., 2009. The anatomy and phylogenetic position of the Triassic dinosaur Staurikosaurus pricei Colbert, 1970. Zootaxa, 2079(1), p.e56.

 

Grillo, O.N. and Azevedo, S.A., 2011. Pelvic and hind limb musculature of Staurikosaurus pricei (Dinosauria: Saurischia). Anais da Academia Brasileira de Ciências, 83(1), pp.73-98.

 

Grillo, O.N. and Azevedo, S.A., 2011. Recovering missing data: estimating position and size of caudal vertebrae in Staurikosaurus pricei Colbert, 1970. Anais da Academia Brasileira de Ciências, 83(1), pp.61-72.

Short Video

Staurikosaurus is not very well known, in terms of media presence and general availability of quality fact pages on the internet. There are a few notable pages, such as the NHM in London, KidsDinos, and the DinosaurFacts website. These pages are all summarized, for the most part, in the WizScience slide show/video that has been made for Staurikosaurus shown below.

Brazilian Theropod

Herrerasaurids make up some of the earliest dinosaurs and the earliest theropod dinosaurs as well. These small carnivorous bipeds are known for their agile appearances and small stature as well as their basal characteristics that laid the groundwork for their descendants, even some of the characteristics that can be found in the latest theropods like tyrannosaurids and abelisaurids. These characteristics were modified over time of course, but the changes can be traced back to these small herrerasaurid dinosaurs that have mostly be found in South America from a number of different locations. One of these locations, in Brazil, was the discovery site of an animal known as the "Southern Cross lizard", Staurikosaurus pricei. The specific epithet honors one of Brazil's first paleontologists, Llewellyn Ivor Price, who collected the fossil which was later described by Edwin H. Colbert. Staurikosaurus was Brazil's first discovered and described dinosaur, but has remained a very uncommon find, meaning that either it was not native to an area that allowed for easy fossilization (such as a forest) or was simply uncommon in its environment.

Staurikosaurus was one of the first dinosaurs and that makes its fossilized remains just as important in understanding the rise of dinosaurs as those of Herrerasaurus and other dinosaurs considered to be the first members of the dinosaur clade. Its long slender limbs appear to have been well equipped for running; forelimbs are missing from the fossil record so we do not know if was good at catching its prey. We do know that its jaw was filled with many serrated and recurved (curved toward the back of the skull) teeth, so it could have caught prey with its mouth rather than with hands. These teeth were also able to slice into its prey. As far as predators of the Late Triassic are concerned, Staurikosaurus was likely a fearsome foe for many smaller reptiles and mammals that it lived with.

©Nobu Tamura

Socketed Teeth

Thecodontosaurus was named for its teeth. Thecodont teeth are situated so that the base is completely enclosed in a bony socket, like our teeth and the teeth of other mammals, crocodilians, and dinosaurs. To help visualize this refer to the image below.

The specific epithet refers to the ancient age of the animal. John Morris, the English geologist who provided the specific epithet in 1843, simply appended the name antiquus to Thecodontosaurus, attributing the name to Henry Riley, the surgeon who helped with the excavation, without any explanation. Therefore we do not know what Morris was referencing with the name T. antiquus. It could be either the fact that it was a fossil animal or that it came from Triassic rock. We may not know any time soon.

Over 245 fragmentary specimens of Thecodontosaurus are known, all attributed to this single species; not for a lack of trying though as 14 other species have been named only to be reassigned to other genera or re-folded into the single valid species. A second species was speculated in 2000 by Benton et al., 2000 when observing more robust specimens of Thecodontosaurus. In the same paper the authors stated that the more robust morphology was equally as likely a result of sexual dimorphism as it was a potential additional species. Regardless of the findings of the paper as regards sexual dimorphism or secondary species, two morphologies are acknowledged simply as gracile and robust.

A Short Short

Thecodontosaurus is not very famous in terms of on film presence (for many dinosaurs this translates simply into "not very famous" at all). However, the University of Bristol started a program in 2000 to engage and educate the public using the research and expertise of university faculty in conjunction with local (and global) fossils and the research that has gone into them. Thecodontosaurus is a dinosaur that was featured heavily in the Bristol Dinosaur Project because it was a very local (read found near, around, and in Bristol) dinosaur that made for an engaging animal in the initial stages of the growth of the Bristol Dinosaur Project; the project originally centered around the recovery and preparation of Thecodontosaurus specimens in addition to the outreach components conducted by the faculty. In fact, the mission statement is still mostly concerned with laboratory work on Thecodontosaurus specimens, but the outreach component appears to continue to be a very valuable portion of the work. The website is a little outdated and other news sources only cover up to the funding cycle for 2013, though the Bristol Zoo (which partnered with the university for some time) last mentions their dinosaur exhibit during the summer of 2017, so there is hope. Anyone that knows more about the project's current state is encouraged to share more with us, but we can only hope that a wide-reaching scientific and educational project like this is still in effect.

A Learning Video

WizScience with a summary video of facts for you to learn some more general information about Thecodontosaurus on this wonderful Sunday:

Additionally, there are a number of pages that have fact files, many different visual interpretations, and a fair bit of discussion about the dinosaur and what we know about it.

Thecodontosaurs

An early socket-toothed sauropod, Thecodontosaurus antiquus Morris, 1843, was discovered in Southern England from Late Triassic (227-205 million years ago) soils around 1834. As many of these stories go, the people that found the remains were academics that could have been called doctors, naturalists, or scientists, depending on the definition they decided to use. A surgeon, Henry Riley, and the curator of the Bristol Institution for the Advancement of Science, Literature, and the Arts, Samuel Stutchbury conducted an expedition in a Bristol quarry where "saurian remains" were reported. Most of a skull was recovered, leading to descriptions of the teeth and name of the animal: Thecodontosaurus meaning "socket-toothed lizard", referencing the way in which the teeth were socketed in the jaws. 

Other fragments of the fossils represented various portions of the entire skeleton including the neck and "body" (ribcage and vertebrae), forelimbs, and legs led the initial description to identify Thecodontosaurus as a dinosaur; the fifth known and named dinosaur in fact. This diagnosis has not changed (some dinosaurs and non-dinosaurs identified in the earliest days of paleontology have been rediagnosed any number of times in the past 200 years) and has actually been supported by more material being recovered and identified. This is a good thing for many reasons, including that the holotype was destroyed in a 1940 bombing raid of Bristol by the German Luftwaffe.

Fame and the Dinosaur

Tawa hallae is a famous early theropod not only because of its coverage by the National Science Foundation or the publication of its description in Science. Tawa is also famous because it was an early theropod situated between the earliest theropod dinosaurs we know, animals like Herrerasaurus and Eoraptor, and the previously considered base of the theropod tree: Coelophysis and its family members. In a way that makes Tawa a kind of "missing link" (a term that scientists do not generally actually like using because it has been so warped). Tawa may be a link between those South American theropods and the rest of the theropod family, but that does not mean it is the only link nor that it is the most important link. The fame that its current status has given it, though, has been immortalized in books, television, online videos, and it has even become a model and toy that is loved by many children (and adults); there is even a new model for this year.

Science Descriptions

When an article appears in Science it is typically accessible forever. In terms of Tawa hallae this is very good news for us because the describing and naming paper are housed and available on the website. The paper is stored as a PDF and as html (Nesbitt et al., 2009), which is nice when you do not want to download another PDF and instead just want to read a paper on your screen. The high resolution photographs of bone and approximated skeletal drawings are available too in this format. This is not the only paper to describe Tawa or its family line though. There are a number of other descriptions of Triassic animals that call upon Tawa and other known dinosaurs for comparisons. However, the other paper linked here today is a little more inference based in that it discuss soft tissues of Tawa that are not actually preserved in the fossils. Instead, Burch 2014 uses osteological correlates of muscle attachments and inferences from extant phylogenetic brackets to reconstruct the muscles of the forelimb in Tawa. These kinds of studies are of interest to me because I have done similar things in the head, but muscle reconstruction in dinosaurs, even if one does not do this type of work themselves, is interesting and important in learning how dinosaurs lived, survived, and died in their environment.

Tawa and the National Science Foundation

The National Science Foundation (NSF) was all over the discovery and naming of Tawa hallae, with good reasons, and because of their coverage we have an entire page of videos on not only the dinosaur but also the discovery and an interview with Sterling Nesbitt, who led the paper naming the fossil. Rather than pasting all of the videos into today's entry, the NSF has been kind enough to place all of the videos on the same page, so we only have to use a single link. Also, rather than describe each video here, the NSF page has done that for us as well. There is a lot of information on this page, and it doesn't take a whole day to go over it, so enjoy the videos and information and then enjoy a Sunday outside, or watching the World Cup; whatever you enjoy!

Coming Back with A Sun God

First, it is really nice to be able to sit and write something for this page again. The past few months it has been difficult to work on writing all day long and then have any energy at the end of the day to write for the page. However, this week, at least, I can spend some time and brain power on writing for the page. This is a good thing.

This week we are going to go back a little further in time and talk about an animal that has, as I find it, strangely not made its way onto the page before. Named for the Hopi word for the sun god of the (all, not just Hopi) Pueblo people and the founder of the Ghost Ranch Museum of Paleontology, Ruth Hall, Tawa hallae was a small Triassic theropod contemporaneous with Dromomeron, Chindesaurus, and potentially even the well-known dinosaur Coelophysis. Tawa is known from a number of different skeletons, none of which are entirely complete, and the initial fossils are thought to be from a juvenile specimen, meaning that the pieced together full version of the animal, weighing in at 15 kg (33 lb) and measuring 2.5 m (8 ft 2 in), is a rough estimate of adult size. The difference between known juvenile and estimated adult size leaves us with a gracile early theropod dinosaur somewhere in the size vicinity of corgi in weight but a golden retriever or a slightly larger dog in height; lengths do not translate to dogs well so I do not know what to give you as a comparison for that measurement.

©Nobu Tamura

Despite living 215-213 million years ago and being one of the more successful carnivores of its day, the size of Tawa was nothing to some of the chief herbivores of the day, such as Plateosaurus (214 to 204 million years ago). Though these two animals may have never crossed paths (Plateosaurus is known from European fossils and Tawa from North American fossils exclusively), the size difference would have likely made it nearly impossible for Tawa to prey on a healthy individual because it was a full 2.3 m (8 ft) shorter and 585 kg (567 lb) lighter than the smallest known Plateosaurus. Sick and injured individuals are always a different story and perhaps Tawa had some way of dealing with large prey like this that we do not know about yet. Regardless, I bring this up only to state that not all of the animals of the Triassic were small and that early dinosaurs were already attaining rather varied sizes. The diet of Tawa was not reliant on such large animals, however, as other small archosaurs, therapsids, insects, phytosaurs, and many other animals were available as part of the diet of this small (for a theropod) carnivore.

Bit Role Star

Rhamphorhynchus appears in two popular films for brief periods in each. The first, One Million Years B. C. is vintage Ray Harryhausen stop motion work with a very inaccurate version of Rhamphorhynchus attacking a Pteranodon. Despite its terrible inaccuracies it is an intriguing interpretation of the animal. Also it eats the Pteranodon nestlings, which is peculiar and very much outside of its inferred diet. The second appearance of Rhamphorhynchus that is probably better known is from Walking With Dinosaurs (Ep. 3 Cruel Sea) in which it is shown skimming the surface of the water for small fish. There are a number of reasons this is a strange portrayal, and time permitting, we will get into them later this week. For now, though, enjoy these two clips:

Night Flying

If a niche exists in nature, some animal somewhere is, was, or will be an expert in that lifestyle. During the Jurassic Laurasia, the northern supercontinent, was populated by a number of pterosaurs that possessed different body shapes and populated different niches. Many different characteristics of these fossil flyers have led researchers to many inferences of diet, flying style, and even time of activity; for example, the scleral rings and orbit shape of Rhamphorhynchus are a key characteristic leading researchers to infer a nocturnal lifestyle. The long-tailed pterosaur has been discovered across Europe and in parts of Africa in deposits that represent shoreline and off-shore environments. The localities, along with cephalopods and fish that have been recovered from both gut areas and coprolites (fossilized feces), point to Rhamphorhynchus as an ocean-going pterosaur. Consisting of three recognized species (R. longicaudus Münster, 1839 (type specimen) , R. muensteri Goldfuss, 1831 (originally Ornithocephalus) and R. etchesi O'Sullivan and Martill, 2015), Rhamphorhynchus was a small (1.26 m, 4.1 ft long; wingspan: 1.81 m, 5.9 ft) needle-toothed pterosaur lacking a crest and possessing a long tail, something pterydactyloid pterosaurs (the kind most people think of when they think of pterosaurs) noticeably lack. The tail, in fact, is the origin of the specific epithet of the type species, R. longicaudus.

Louis Figuier, 1863

Yates Description

As with many dinosaurs, there are a number of papers that mention Dracovenator, far more than the number of papers that actually focus all of their attention on our featured dinosaur. The description of Dracovenator by Yates (2005) is detailed, including line drawings, detailed photographs, and even a character list of attributes at the end of the article. As with many descriptions, the article is a little dry, but that is the nature of descriptive paleontology, so it does not make the article bad or otherwise lacking some sort of thrill found in other papers describing fossils. I am kind of a fan of the image of the juvenile fossil displayed upright as it is not often that we are shown the flat side of fossils in papers in this manner.

Yates, A. M. (2005). A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods. Palaeontologia Africana 41:105-122

Dragon Hunters

Dinosaurs and fossil hunters have been referred to as dragons and dragon hunters for centuries now; however, there is only one dinosaur whose name means "Dragon Hunter": Dracovenator regenti Yates 2005. A dilophosaurid discovered in the South African foothills of Drakensberg ("Dragon's Mountain": Dutch), Dracovenator consists of cranial material from early Jurassic rocks near the borders of Lesotho, a small country contained within South Africa. The characteristic shape of a dilophosaurid skull is apparent in the remains of Dracovenator in both the adult (holotype) and referred juvenile materials (reassigned from Syntarsus to Dracovenator by Munyikwa and Raath 1999). The estimated size of Dracovenator, extrapolated from related animal sizes and the cranial material available, is between 5.5 and 7 meters (18 and 23 ft) from snout to tail and weighing upwards of 400 kg (882 lbs).

Dynamic Images?

What is the most dynamic, awe-inspiring image of Tuojiangosaurus that one can find on the internet? There are a near infinite number of opinions regarding which image and why any particular image might be the most beautiful or amazing image of Tuojiangosaurus. The images could come from anywhere also. This includes skeletal mounts, 3D video game renders, ink drawings, and any other media one can think of. My personal favorite was a hard choice this week. I always love the old-fashioned (like Charles R. Knight style) sorts of drawings, but Tuojiangosaurus was not discovered until 1977. Conversely, I appreciate really well done computer generated media as well, of which there is plenty representing Tuojiangosaurus. The image I have chosen as my favorite of the lot comes from the latter category today, and specifically it is attributed to Román García Mora. Even though the artwork is attributed to Mr. Mora, it does not appear on his website, linked above. Maybe more unfortunate, the image was originally found on a fourth party site and therefore even farther from the artist's control.

©Román García Mora