Tag Archives: paleontology

Two dinosaurs become one

Earlier this year a paper was published (Scannella and Horner 2010) on one of the most well-known dinosaurs of the Late Cretaceous, Triceratops, updating our understanding of not only this dinosaur species, but also maybe influencing our view of many other dinosaur species as well.

Triceratops

Triceratops as mounted at the Carnegie Museum of Natural History

Triceratops was first described in 1889 by O. C. Marsh, and has become one of the best represented dinosaur species in terms of numbers of fossils recovered. Their remains are very common in the Hell Creek Formation of Montana and the Dakotas. And, Triceratops has been known by practically every kid for the last 100 years, being well represented in dinosaur movies and dinosaur toys the world over.

Triceratops is best known for its three horns and neck frill of bone. Torosaurus, another dinosaur that is obviously related to Triceratops because of its similar appearance, was also first named by Marsh in 1891. It is found in the same geologic units in the same region, but is much less commonly found. Torosaurus was much larger than Triceratops, and had large openings in the neck frill, and its horns pointed more anteriorly.

So, for over 100 years paleontologists thought there were at least two species of horned dinosaurs in these beds. But scientific understanding makes progress. In the early “bone rush” days of the nineteenth century the game was naming new species. Today, there is a trend of relooking at those species to see if they are in fact different.

Torosaurus

"Torosaurus" mount at the Milwaulkee Museum, now should be called Triceratops.

This is where the new study comes in. The authors examined Triceratops and Torosaurus and questioned whether they might not be the same species, but at different life stages. It has become apparent that individuals of a species can change a great deal over their lifetimes. A newborn human does not look much like an adult in body proportions, for example. If past species also changed significantly over their lifetimes, the different stages could easily be mistaken as completely different species. And that seems to be the case here.

By looking closely at the trends of skull shape and indicators of maturity, Scannella and Horner believe that in fact Torosaurus individuals are older and more mature individuals of Triceratops. This means that later in their development individual Triceratops specimens changed significantly as they reached maturity, developing the large openings in the neck frill and increasing in overall size.

The implications for other dinosaur species are clear. If individuals can change dramatically during their lifetimes as they mature, perhaps there are many named dinosaurs that are not truly different and unique species, and we need to match youngsters with adults. No doubt this will keep paleontologists busy for the next 100 years.

And in case you are worried, the name Triceratops will remain, since it was the first name given to the species that we now realize includes those individuals that one were called “Torosaurus.” So, despite some headlines Triceratops did (and still does) exist!

Scannella, J. B., and J. R. Horner. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4):1157 – 1168.

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I am a paleontologist

I love the science of paleontology for many reasons. The science combines so many other areas of study into one bundle, such as geology, biology, functional morphology, evolution, stratigraphy, and systematics.

Not only that, dinosaurs and other prehistoric animals are just fun! And being fun, paleontology is a great way to introduce people to science in an engaging way. How many young people start their interest in science by learning about dinosaurs, and say they want to be a paleontologist when they grow up–a bunch!

Well, someone shared this video with me and I love sharing it with you. Enjoy! (you may need to scroll down).

Related Posts: check them out.

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Why dinosaurs are not extinct

In the twenty plus years I have been involved in paleontology I have been witness to a revolution within science. The revolution has been quiet, not noticed by most of the public. Like any good revolution, the battles of this revolution took place between two camps, the “traditionalists” and the “radicals” who were out to change things. And this shift is illustrative of how science as a whole moves from one way of understanding to a brand new way of looking at the world. It is, in fact, a paradigm shift that has profoundly changed biology and paleontology forever.

At issue is how we explore and classify the relationships of all living things. The traditional view, the one that I was taught as a young student, was the classification of living things into the taxonomy originally begun by Carl Linnaeus. This system started with a group, and then sought to put things into the group. For example, one can make the observation that animals that look like “dogs” could be grouped together, so you would start with the idea of a dog-group and look for animals that should be included.

You might put foxes, wolves, domestic dogs into the group, and call it the dog family. You might also note that “cats” could likewise be grouped, and do the same thing, creating a cat family. In this view, the families were equal in rank—and there could be no overlap. An animal would be included in only one of the equal-ranked families. Any animal was included in only one class, for example Amphibia, Reptilia, Aves, or Mammalia.

The equal-ranked heirarchy of classifications worked well enough when we mainly were concerned with modern animals. Clearly, birds look different than mammals and reptiles, so it seemed evident they belonged in their own class. But this classification scheme, however well it served us as a place to start, is myopic about how evolution actually operates—how organisms actually evolve. This is understandable since it was started 100 years before evolution as a theory was established.

In trying to shoehorn life into the system, we repeatedly ran into problems as we expanded our knowledge of the diversity of living things and our understanding that the history of life is a complex branching bush. We knew that early tetrapods (organisms with four limbs) gave rise to the early amphibians that crawled out on land, and that they in turn evolved into reptiles, mammals and birds. But despite this branching within tetrapods, the class ranks were forced to be exclusive, so somewhere in evolutionary history was an “amphibian” that had to become a “reptile,” and a “reptile” that had to become a “bird.”

The many transitional forms in the fossil record increasing became impossible to classify. These intermediate animals had to be forced into one class or another. Increasingly, it became evident that many times the criteria used to put an organism into one class were the whims of an individual scientist, and another equally qualified expert with different opinions might place the same animal in a different class with equal validity.

The origin of birds was for a long time a great mystery to paleontologists. Birds are a pretty unique and specialized group, and while we knew that they originated from reptiles somehow, exactly how and when was unclear. One early paleontologist noted that dinosaurs had many features in common with birds, but the early concepts of what dinosaurs were like distracted most scientists from comparing them too closely. After all, the common conception of dinosaurs was as big, lumbering, dim-witted, swamp-dwelling beasts. The bird ancestor must have been light, fast moving, and energetic.

However, dinosaur research over the last thirty years has completely changed our view of them. Evidence from many lines, including things like footprints and the cellular structure of the bones, all point to dinosaurs as being very dynamic creatures. With this new view, the notion that birds were linked to dinosaurs became clear too. Now, we have dinosaur fossils with feathers, and birds with teeth and dinosaur tails to attest to their close relationships. In fact, birds are most closely related to the meat-eating raptor-like dinosaurs of Jurassic Park fame.

To go along with the revolution in our view of dinosaurs was that revolution in science that I mentioned above–the emergence of a new way to understand the interrelationships of life on Earth. This new model accommodated the myriad branching events that life actually experienced in order to produce the great variety of living things. So, instead of starting with a conception of the group and looking for members, this new concept looked at the branching patterns evident in life, and then sought to apply names.

Below is an illustration of the branching pattern of selected tetrapods, those vertebrates with four well developed limbs. As the first tetrapods gave rise to new and different groups, the branches split off. An early tetrapod gave rise to amphibians and the other animals above it on the chart (mammals, turtles, etc.). A later tetrapod developed traits related to the production of eggs and young that we recognize as the Amniota. Some of those early amniotes went off on an evolutionary trajectory that we can recognize as being the early mammals, and all the diversity that resulted from them. And so it goes up along the branches.

Branching pattern of the tetrapods, mostly the land vertebrates

Branching pattern of the tetrapods, mostly the land vertebrates

We now explore the branches and can apply names to the groups that we find to be meaningful. For example, in the illustration below we can call everything in the box a reptile. Note that it includes things that used to be called reptiles, turtles, lizards, snakes, crocodiles, and dinosaurs, but now also includes birds.

Group that includes all the reptiles

Group that includes all the reptiles

Likewise, if we draw a line around the dinosaurs, they also include the birds. This view of life tells a more complete evolutionary history and retains the branches, letting the animals “fall where they will.” We do not pull birds out of their relationships and give them special consideration. Instead of birds being equal in rank with reptiles, they are included among them. This upsets the tradition that being a bird is somehow equally important to being a reptile, but better reflects the reality of descent, without forcing nature into earlier human conventions of naming and grouping. Of course, birds are a group within their own right, and we could zoom in to explore their branching pattern, but it does not change the group to which they belong.

Group of dinosaurs

Group of dinosaurs

This leads to another startling statement. Below I have highlighted the groups that are extant (still around today).

Groups of tetrapods that are alive today (extant)

Groups of tetrapods that are alive today (extant)

Because of our grouping scheme, birds are included in the dinosaur group, so dinosaurs are not really extinct! They live among us today flitting about, singing their mating songs in the trees. It is funny how things can change in science. Twenty years ago scientists would have told you the dinosaurs were all extinct, and today we say the opposite. I love scientific progress–it can be so startling.

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Scientifically Authenticated Dinosaur Model Kits Now Online

Guest Post

For the Dinosaur connoisseur and collector, you will find what you have been looking for at Dinosaur Model Toys.com. The creator of all the works featured on this site is not only a gifted sculptor, but actually works with dinosaur fossils as a paleontological reconstruction artist, fossil preparator, and field technician at the Natural History Museum of Los Angeles. His artwork is based on the latest scientific research, real fossil material, and years of hands on experience. This is why the work featured is regarded as some of the most scientifically accurate available to the public.

The new Dinosaur Galleries at the Natural History Museum of Los Angeles will feature many of the artist’s creations. Most notable is the baby Tyrannosaurus rex estimated to have been two years old when it died, for which nearly ninety percent of the skeleton will be recreated for this mount. This sculpted reconstruction will be featured with two real T-rex specimens, one a six-year old, and the other the sub adult specimen named “Thomas” which Doyle Trankina helped collect, and prepare. Thomas is estimated to be about seventy percent complete, making it one of the top five most complete in the world. Our initial offering will be a series of cast resin models and limited edition bronze sculptures with both a highly detailed exterior view, and a rendition of the internal skeletal anatomy of an adolescent T-rex similar to the Thomas find.

As part of the Dinosaur Institute at the Natural History Museum of Los Angeles Doyle Trankina has attended several field excavations in Montana, Utah, and the Mojave. While in the field Doyle prospected, and assisted in the collection of several specimens, most notably Thomas the sub adult Tyrannosaurus rex that will be gracing the museum’s new Dinosaur Gallery in 2011. Through his experiences with the museum with his private obsession with prehistoric life and the natural world, Doyle has produced several sculptures and illustrations for exhibition and publication. Doyle has an extensive list of sculptures to produce over the next two years. His work will require lots of observational study from the museum’s collection, and extensive extrapolation based on the latest research, and modern analogues like birds, and crocodiles.

After completing the preparation of Thomas, Doyle embarked on a half skeletal, half flesh reconstruction of an adolescent Tyrannosaurus rex at 1;24th scale. The detail and fidelity to the skeleton was accomplished by long study of the anatomy from several existing mounts, scientific publications, and photographs from the some of the best Tyrannosaurus specimens. The teeth were surfaced to provide the accurate thickness and semblance to where the tinny serrations would have lined the many teeth. Because the position of the serrations actually change on the teeth as they move back towards the throat, the ridge implies the appropriate location of the serrations. The scales were carved individually so that the skin wraps around the form in a realistic, and accurate way.

Doyle is currently working on a skeletal reconstruction of a baby Tyrannosaurus rex which will be mounted in the new Dinosaur Galleries with Thomas and an intermediate specimen as an illustration of age progression. The actual specimen is only known from a skull fragment from the snout of what is believed to be from a two-year-old Tyrannosaurus rex. There are no post cranial remains, and there are only a handful of examples that are believed to be that of baby dinosaurs. This project has just begun, and with Dr. Chiappe Doyle will be making history in presenting the worlds only mounted baby Tyrannosaurus rex specimen.

Fall of 2009 marked one of the biggest Paleontology news splashes, featuring N. America’s smallest dinosaur, Fruitadens haagarorum. Nearly 150 million year old, the tiny Fruitadens would have shared its life with such titanic beasts as Brachiosaursus, and Allosaurus in the late Jurassic. It is thought that the animal might have weighed as little as two pounds and measured only 28 inches in length. Fruitadens was discovered in Colorado in the late 1970s in a geological formation known as the Morrison, more specifically in an area called Fruita, for which the specimen was named after.

Artist reconstruction of the dinosaur Fruitadens

Artist reconstruction of the dinosaur Fruitadens

The strange dentition of this animal implies that Fruitadens might have been omnivorous, eating plants and at least insects if not small vertebrates. Doyle has produced the first and most accurate illustrated and sculpted reconstructions of this animal. Fruitadens belongs to a family of early dinosaurs called heterodontosaurids, which share many interesting features, one of which are the teeth. Fruitadens like other heterodontisaurids have varied dentition, and in the front of the mouth sits a canine like tooth on the lower jaw. His work was featured on every major news source in the world, and five of the sculpted Fruitadens will be featured in the new galleries in 2011. In his studio, Doyle is currently working on a scale Fruitadens, which will be approximately 30cm long . This will be the only scaled sculpture of the animal, and the first and only for sale. The full scale version is not for sale and can only be seen at the Museum.

Doyle is also concurrently working on Mamenchisaurus, a long neck dinosaur and part of the branch of Sauriscian (lizard hipped dinosaurs) known as Sauropods. As the prospects of obtaining a casting of the Chinese mamenchisaur skull proved too difficult, Doyle was charged with the task of reconstructing the skull from two dimensional reference and other dinosaurs like Camarasaurus for comparison, and to gain familiarirty with Sauropod skull anatomy. The rare skull was found in China and researchers provided a paper with a detailed description and several scientific illustrations. Sauropod skulls are rare because they are so frail in construction, have several small bones that usually disarticulated some time after the animal dies, and are not commonly preserved in fossilization, or are so disarticulated and in such small pieces that they are nearly impossible to find.

Doyle Trankina is a sculptor, illustrator and fossil preparator at the Los Angeles Museum of Natural History. For unique scientifically authenticated Dinosaur Art, Dinosaur Models and Dinosaur Resin Model Kits, visit his online store Dinosaur Model Toys.Com.

Many other interesting dinosaur facts can be found here at Boneblogger.

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What is paleontology

What questions fall within the purview of “Paleontology”?

Quite a wide variety, it turns out, because paleontology is the study of prehistoric life – the exploration of the entire history of life. Since 99.9% of all species that existed are now extinct, that is a lot of biodiversity. The science is multifaceted and diverse because the topic is equally diverse.

Because of the connections with geologic time and rock formations as the context of fossils, most paleontology classes are offered through geology programs at universities. I LIKE teaching introductory courses in geology because I find that people frequently end up taking geology in college as a last resort. Students generally are required to take a science class with a laboratory and they too frequently review their options without much enthusiasm. They took biology in high school and did not like it then, so want to stay away from that now. Chemistry and physics sound like a lot of math, so that leaves geology, they reason.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visable in the middle foreground.

Fossil collecting in western Kansas. A partial mosasaur skeleton is visible in the middle foreground.

On the first day of geology class I like to point out that the study of the Earth and its history involves biology, chemistry, and physics, so we will cover them all. There is usually a little moan from the class at this, and I enjoy my moment of sadism. Paleontology in particular incorporates biology and geology to a very high degree, because to study fossils you have to fully understand the animals as well as the history that you can read from the rock record.

So could we come up with a classification, not of fossils, but of paleontologists?

Since the topic is so multifaceted the science falls naturally into several key areas. For example, individual paleontologists tend to be more oriented toward either geology or biology. The first group might be more interested in the animals themselves: how did they live; how did they move and capture prey; how did they relate to other organisms in their environment.

The second group might be more interested in what the animals can tell them about the Earth’s history: what do the fossils tell us about the movement of plates over the Earth’s surface through time; when did different animals live in geologic time so we can estimate the age of rocks; that sort of thing.

Of course, this is an over simplification.

Paleontologists can also be classified by which group of organisms they work with. Is it plants (maybe fossil forests made of ferns), or invertebrates animals — marine or terrestrial – ranging from the largest squid ever known to fossil spiders, or maybe vertebrate animals.

A lot of the people I know are paleontologists, and they tend to be people with diverse interests, often ending up doing a bit of all of it. For example, many years ago I worked on a fossil locality in southwestern Kansas that included plant, invertebrate, and vertebrate fossils. Having all the groups of organisms was critical to interpreting a much fuller picture of the ancient environment there than any one of the groups alone could have provided.

As a paleontologists I must be a “jack of all trades,” and that is one of the things I love most about it.

Other interesting facts can be found here at Boneblogger. Enjoy.

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