Ankylosaurus- The Body

Postcranial remains of Ankylosaurus are known but the focus of many of the descriptions of the postcranial elements is the osteoderm armor and the massive clubs that constitutes the caudal end of the tail. Armors gave the dinosaur its name and the postcranial armor of the dinosaur is extensive. The armor started on the cervical vertebrae with half rings of armored bone. The ribs of Ankylosaurus were wide and strong to hold the soft tissues of the gut. Superficial to the ribs there are osteoderm plates that constitute the external armor scutes. These osteoderms are unique to individuals and have the potential scars to prove that they were effective; not all of the fossil remains recovered have pathological issues and that statement is more based on things that could be possible than things that are known for sure. The osteoderms continue caudally along the body and onto the tail where the final two osteoderms are expanded into a club. The club even has a handle; the seven caudal-most vertebrae are ossified and bound by ossified tendons to create an immobile base for the oversized osteoderms of the club.

Dorsal view of AMNH Ankylosaurus

Famed Dinosaur

Ankylosaurus is a well known dinosaur. Appearing in many documentaries, movies, and in popular literature has allowed this dinosaur to become a common dinosaur name and introduced it to other aspects of the world. This includes video games and television shows as well as children's books and as the centerpiece, or an integral part, of many museum's dinosaur collections around the world. This last part seems a little odd since there are only three known skulls, but it is nonetheless true. In the most recent string of famous Ankylosaurus depictions, the Jurassic Park series, including Jurassic World, are probably some of the biggest portrayals of the dinosaur. However, long before this Ankylosaurus was featured in the 1980's cartoon Dinosaucers as a bad guy Ankylosaurus from space who was rather pig-like. One of my favorite adaptations of Ankylosaurus for popular media was in the Dinotopia series. James Gurney's world where dinosaurs and humans lived together portrayed ankylosaurs as benevolent dinosaurs that can carry large loads. In the miniseries that aired in 2002 a wild Ankylosaurus rampaged across the screen but was soothed by a young girl who discovered the dinosaur was suffering from a toothache. The story is a little Disney-like, but it is worth watching and it is one of the better depictions of Ankylosaurus.

Ankylosaurus- The Skull

Photo by William Diller Matthew

There are three known Ankylosaurus skulls. Those three skulls are similar but have noticeable differences; the reigning idea is that the differences are taphonomic in nature rather than ontogenetic or species related. We know that Ankylosaurus has a large beak and small eyes and that the skull is covered in dense dermal bone and small crests and horns. Of particular note are the jugal horns that face ventrocaudally and give the skull a triangular appearance in lateral view. The teeth of Ankylosaurus comprised a large dental battery of up to 36 teeth per side of the mandible and 35 teeth per side in the maxilla. This may be slightly misleading as the only mandible known is from the smallest of the known specimens. There are many more aspects of the skulls that are interesting and strange, but the teeth of Ankylosaurus deserve some specific attention here. The teeth are leaf or spade shaped and mediolaterally compressed. The rostral and caudal margins are covered in serrated lobed denticles. The most caudal teeth appear to have curved caudally meaning that plant matter was processed by the teeth even up to the moment of swallowing.

Illustration by Barnum Brown

Looking Back at Ankylosaurus

Sometimes one of the best things about writing this blog is that I notice that I somehow missed a famous dinosaur. Ankylosaurus has never appeared on this blog and I can therefore share any article without prefacing it with "we already read this but it is worth reading again" because I have yet to share any of them! Williston and Brown originally described the ankylosauridae with Brown receiving credit for the Ankylosaurus himself even though Williston actually published the description for Barnum Brown. Nearly 100 years later, 95 to be exact, Kenneth Carpenter re-examined and redescribed the Ankylosaurus remains of Brown and the subsequent finds since. Descriptions of the dinosaur are not the only interesting papers that have been posted online. There are also papers on Ankylosaurus forelimbs and the paleoenvironment in which they lived. In a very interesting but not unexpected progression, Carpenter and Coombs combined to discuss systematics of Ankylosaurus and it nearest relatives.

Movies A-plenty

Ankylosaurus has shown up in so many movies and documentaries that listing them would take far longer than makes sense when I can simply share a small lump of them. The only problem is that a lot of Ankylosaurus videos is that they do not portray Ankylosaurus. Likewise, there are ankylosaurid videos that concern other taxa but rely heavily, or only actually depict, Ankylosaurus. Here are some videos that show and reference the correct dinosaur though:

Ankylosaurus Facts

There are some random videos with Ankylosaurus facts. There is one that includes a song and some drooling theropods that can be watched at this link here. Fact pages are a little more heterogeneous. LiveScience has a higher level reading passage instead of a list of facts. As usual, Enchanted Learning has a list of facts and a link to a coloring sheet of Ankylosaurus. Other fact lists are hosted on ScienceKids and Mental Floss. Maybe the most entertaining video or list is the I'm A Dinosaur video:

Ankylosaurus Astronaut

The dinosaur of the month on the calendar is Ankylosaurus. This dinosaur is one of the members of the Thyreophora, a group containing Stegosaurus and other armored dinosaurs. The genus Ankylosaurus contains a single species, Ankylosaurus magniventris, meaning "Fused lizard, great belly". Measuring approximately 6.25 m (20.5 ft) and weighing an estimated 6 tonnes (13,000 lbs) one would imagine that Ankylosaurus was a giant dinosaur. The length and weight are rather enormous; however, at approximately 1.7 m (5 ft 6 in) Ankylosaurus was shorter than the average man and only about 2 inches taller than the average woman.The astronaut illustration of this dinosaur is quite impressive despite its short stature, not that one has anything to do with the other!

©Brynn Metheney

Announcements

If you are at or near the University of Missouri on September 30th check this talk out:

Famous Destruction

The size of Spinosaurus made it a much more famous dinosaur than Bahariasaurus back in the days that the two dinosaurs were uncovered and moved to Germany. After the Allied bombing that led to the desctruction of these two specimens the more well known, illustrated, and published Spinosaurus was mourned by science more widely than Bahariasaurus. The lone photo of Stromer with the femur of Bahariasaurus is the only original evidence of the dinosaur. Despite being compared to Deltadromeus, also known from the Kem Kem regions of Morocco and Algeria, we know that Bahariasaurus was of similar size to Tyrannosaurus and not necessarily Deltadromaeus. The connected legacy of Bahraisaurus and Spinosaurus continues on in illustrations such as this, which would appear to be in Todd Marshall's style, if it is not his own work (credit lacking online).

Understanding Size

I mentioned the other day that there are little to no known pieces of evidence of the original Bahariasaurus remains that Ernst Stromer brought back from Northern Africa to Germany. There is, however, a single image of Stromer standing next to a portion of the remains of Bahariasaurus. The femur is appreciably large, considering the typical language and representations of Bahariasaurus in illustrations. We can see, looking at the size comparison of the entire dinosaur, that the femur is actually a little larger than previous discussions may have implied.

©Karkemish (Eduardo)

Photo described as Stromer with the "hip" of Bahariasaurus

Paperless Dinosaurs

Bahariasaurus has all but been destroyed in the modern age. Allied bombing took the original material and time, war, and a lack of preservation has made the illustrations and writings of Ernst Stromer rare and potentially irrevocably lost over time. Some of the only materials that mention, let alone describe, Bahariasaurus are the collected descriptions of Saharan dinosaurs that were put together by Paul Sereno, et al. back in 1996. This material is extensive but unfortunately still lacking in original evidence from Stromer.

Bahariasaurus Movies

There are no actual movies for Bahariasaurus. Rather than wasting time complaining or offering strange alternatives, here are two tribute videos with a series of photos of the animal. The two videos overlap significantly, but they also have differences. Enjoy these:

Bahariasaurus Tributes

Bahariasaurus is not as famous as the other North African dinosaurs like Spinosaurus that are often portrayed in documentaries and movies. Because of this Bahriasaurus has slipped through the popular cracks. There are therefore very few videos; however, there are  number of websites that have some facts about the dinosaur. These facts are generally similar and none of the websites have radically new information about the dinosaur. Dinopedia has a short amount of information written up very quickly and the Dinosaur Database has a map of supposed fossil locations of Bahariasaurus. Prehistoric Wildlife also hosts facts and goes a little more in depth, but it is par for the course today in terms of lack of extended knowledge.

African Predators

Bahariasaurus ingens was unearthed and recovered by the team of Ernst Stromer during the early 1930's. Like many of Stromer's African discoveries, this North African dinosaur was described during 1934 and dates from the oldest Late Cretaceous (Cenomanian) approximately 95 million years ago. Also like most of Stromer's African dinosaurs, Bahariasaurus was destroyed by Allied bombing during Wold War II. Currently questioned as a synonym of the dinosaur Deltadromeus, Bahariasaurus is also currently described as a megaraptoran tyrannosaurid. This tyrannosaur sized dinosaur was a contemporary of the equally sized Carcharodontosaurus but possessed characters that, so far, keep the dinosaur separated from cracharodontosaurids as much as it is separated from tyrannosaurids and megarptorans proper. Without new remains we may never know the exact affiliation of this dinosaur; however, we do not now how long this will take or if it will happen for sure. Discovery of fossils is always a bit of luck and fortune though.

©Nobu Tamura

Jobaria Drawn

A lot of illustrations of Jobaria are typical for sauropods; a giant lumbering dinosaur holding its head high at the end of its long neck with its tail held out behind it. This illustrated posture is not lazy or pointless, in fact, seeing dinosaurs in what would be their most typical daily posture paints a more vivid look of what the daily life a dinosaur would be like. The images we see of fierce battles and dinosaurs in action also belong as parts of the complex lives that the animals lived, but Jobaria, for example, was not constantly hunted and probably did not have to rear up onto its hindlimbs every second of every day in order to grab food items. These action shots of life, like that portrayed by James Kuether, are exciting and integral to understanding how that rearing up action would be carried out by an adult Jobaria. That action is clearly something powerful and intimidating as it would allow this 220 plus tonne dinosaur to make itself taller than its predators and enable it to use its weight as a weapon. This was probably important given that its tail was somewhat short an unable to whip around as effectively as a dinosaur like Diplodocus. Mass can be an effective weapon though, and worth fearing for the small Afrovenator portrayed in Kuetcher's illustration.

©Nobu Tamura

Rearing Up

The mythology on the monster Jobar is rather thin online. However, we know a great deal about the anatomy and general morphology of Jobaria even without knowing if it really looks anything like its namesake. Jobaria has interesting forelimbs that appear to be slightly less robust than their hindlimbs. Possessing humeri that were less supportive than their femora explains the depictions of the dinosaur that we often see with its body sloped such that the weight of the animal is much more posteriorly directed and the center of the weight looks to be just in front of the pelvic area. The ratios of humerus and femur compared to their companions in elephants were the basis of the caudal center of gravity justification based on the idea that thicker femora enabled Jobaria to rear up on its hindlegs to reach into the upper canopies of the trees.

Sketch ©Paul Sereno, photo © Dan Liebman

Jobarian Literature

There are a number of papers on Jobaria that are worth mentioning today. The first is the description of Jobaria. There are other papers as well, though not as many as one might think considering that Jobaria is a very unique and interesting sauropod. There are abstracts from The European Association of Vertebrate Paleontologists conference in 2012 that discuss where and when sauropods fit into the phylogenetic tree together. These abstracts do not specifically discuss Jobaria by itself, but the context of their phylogeny is important in discussing them. Most importantly, for the most current description of Jobaria and its position within its ecosystem, there is a paper on African sauropod diversity that is well worth reading. I would encourage people to read at least this paper out of the three because its got the most current and relevant science on the dinosaur.

Jobaria in Cartoons

There is only a single video that shows Jobaria other than the video shared yesterday. There are a few tribute videos that are nothing more than a stream of photographs and illustrations. That other single video is a fight scene from the Dinosaur King cartoon between Jobaria and Spinosaurus. Dinosaur King, if it was accurate, would not have a Cretaceous and Jurassic dinosaur fighting. However, it is a fairly entertaining cartoon and the clip is pretty fun to watch on its own.

Short Readings

Jobaria tiguidensis is a dinosaur with few lists and many paragraphs. The links for the dinosaur, therefore, are all reading selections rather than lists of facts. This includes sites like Enchanted Learning and Kids Dinos. It also includes a version of these facts, mixed from Wikipedia and other sources, in a WizScience video:

Looking the Same

One of the things that sauropods are generally criticized for looking extremely similar to one another and being composed of highly fragmentary remains. These kinds of generalizations can be applied to a number of extinct animals known only from fossil; that does not make the generalizations any less true in some instances. However, one sauropod that looks somewhat distinctive is the African (Nigerian) dinosaur Jobaria tiguidensis. The dinosaur was recovered from the Sahara desert in 1997 and the simple fact that over 95% of the skeleton was pulled from the site makes this sauropod both one of the most complete sauropods ever recovered and one of the more distinctive and therefore different from other sauropods. Jobaria was an middle Jurassic (~164 million years ago) sauropod that embodied the Taureg legend of a beast with the same name. Jobaria may have been a little larger though starting at 60 feet (18.2 meters) long and 24.7 short tons (22.4 tonnes). Jobaria also had a very unique body posture, if all recreations are accurate:

(C) Steveoc

A Different Version

(C) Gabriel (Kana-hebi)

To end the week of Alvarezsaurus, looking at an alternative view of the dinosaur lends us to some more insight as to how different people have interpreted the skeleton and inferred structures based on where the animal fits into the tree. This illustration makes Alvarezsaurus look a great deal more like a chicken or duck than when looking at the head. The forelimbs have all but disappeared, with those forelimbs being fully enveloped by feathering. Despite looking as though they have been taken into the body, the forelimbs are probably more covered in extended body feathering than they are shortened abnormally, though this could only be answered by the illustrator himself. The remainder of the body is very typical and does not appear to have any different interpretations. However, unique interpretations such as this are always welcome and intriguing because paleontology is a very inference-heavy science and thrives on these kinds of soft tissue inferences, but must be based on solid knowledge of the available anatomy.

The Famed Alvarezsaurus

Perhaps the most famous thing about Alvarezsaurus is the fact that we know it exists. Beyond its improper placement in a documentary there is no other film or television placement of the dinosaur. The lack of popular sentiment for the dinosaur in common mediums is interesting given that it is a fairly well known dinosaur that is famous for being famous. Despite this it is not well represented, as stated before. The dinosaur is mentioned in a few books, though these are mostly passing mentions.

Interesting Anatomy of Small Dinosaurs

The number of specimens and the preservation of those specimens is enough to make a few concrete observations about the anatomy of Alvarezsaurus that we can discuss today. The vertebrae, especially the caudal vertebrae, are well known and the descriptions of the vertebrae are highly detailed, if anyone is interested in the vertebrae; my interest in vertebrae is waning these days. More interesting and unique is the known anatomy of the shoulders and ankles of Alvarezsaurus. The scapula, for example, is smaller, relatively, than other members of the family. It is also curved caudally as one traces it dorsally behind the shoulder itself. The ankle is also special within the family as it does not consist of a fused calcaneus and astragalus. An unfused ankle and a small, curved scapula are apparently basal within the alvarezsauridae, as Alvarezsaurus is often described as a primitive form within the family that bears its name. These features are hard to see in this mounted skeleton, but they are there.

Not Online

The original Bonaparte 1991 description of Alvarezsaurus calvoi is not online in any easily accessible place. There are a number of early 1990's taxa that are missing their initial descriptions online, so this is not an important distinction. That description makes the video from yesterday impossible as it describes a dinosaur from up to 83 million years ago whereas Saltasaurus comes from rocks dating to approximately 78 million years ago. Despite that trouble, the description has been used over and again in describing other members of the alvarezauridae such as Albertonykus and Achillesaurus.

A Minor Role

Alvarezsaurus has had only a small role in a documentary so far. The documentary is Dinosaur Planet and the small dinosaur appears in the fourth episode. Its role is as a small predator, obviously, of young sauropods; in this instance the sauropod in question is Saltasaurus. The attack is shown at night and the almost ostrich-like dinosaur manages to snag a few little sauropod snacks on its hunt. The attack occurs around minute 18 of the video shown below. The embedded version should start at 17:30.

Dinosaur Planet - Alpha's Egg by arkoleon

Drawing Your Coloring Sheet

Alvarezsaurus can be drawn, like any other dinosaur, and there are instructions on how to do so online in the 123Peppy drawing series. The website is actually geared toward entertainment, games, and social activities for young ladies, but they host a lot of drawing tutorials and other interesting videos on YouTube. This dinosaur is a little cartoon-like, but it is also still quite interesting. All of the facts related to Alvarezsaurus are also captured in the I Know Dino podcast; we have mentioned this podcast once before. The podcast takes the place of reading multiple sites.

Alvarez and Argentina

The small insectivore Alvarezsaurus calvoi was a bipedal theropod with a long tail that was built like a running machine. The little speedsters ran around Argentina from approximately 86 - 83 million years ago. Having been described as an avian-line theropod and as a non-avian theropod, Alvarezsaurus has had a strange past, taxonomically. Despite these difficulties Alvarezsaurus is an interesting dinosaur in an interesting position of the tree of life. As a relatively complete fossil, the skeletal anatomy of Alvarezsaurus is highly informative, regardless of the direction of the resulting tree branches that follow Alvarezsaurus.

©Karkemish

Classical Art

As one of the more well known ceratopsians, in recent years at least, Pachyrhinosaurus has influenced a lot of modern dinosaur art. Possibly one of the most dynamic of these images is this illustration of P. perotorum recovered from Alaska. The immense size of the animals is conveyed not only in the way they and their massively ornate frills fill the frame, but also in the two small shorebirds almost entirely hiding in the plain sight of the foreground. These birds are labeled Gruipeda vegrandiunis, representing a taxon represented by ichnofossils, in this case footprints.Regardless of the size of the birds, the dinosaurs are appreciably immense. Their heads are large bulky ends to a 26 foot (8 meter) long body that, with the power and muscle that was most likely behind it, would have been capable of delivering powerful and devastating attacks. We can assume, however, that attacking another animal with their head was probably, as it is even in goats and other animals we see with dedicated striking apparatuses for heads, a last resort during confrontation. Displays, territorial, and mating disputes may have been another question all together (see goats at play; I do not have to link anything specific, people love goat videos).

©James Havens, This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.