Pachyrhinosaurus: Prehistoric Beast of the Week

This week belongs to a unique ceratopsian dinosaur, Pachyrhinosaurus!  Pachrhinosaurus was a very successful plant-eater that lived in what is now Canada and Alaska during the Late Cretaceous period.  There are actually three different species within this genus that range in age from 73 million to about 69 million years old.  Pachyrhinosaurus was one of the largest ceratopsians, the biggest individuals measuring over twenty feet long from beak to tail.  The name, Pachyrhinosaurus, translates to "Thick Nose Dinosaur".

Pachyrhinosaurus perotorum life reconstruction in watercolor by Christopher DiPiazza.

While many other ceratopsians had horns growing from their noses and brows, Pachyrhinosaurus had a wide, flat structure called a boss, earning it its genus name.  In addition to this boss, Pachyrhinosaurus of all species had horns growing out of their frills.  Some curved outwards, while others curved more dramatically downwards.  There is even a decent amount of variation among horn shape and length among adults of the same species.  This could be due to age or even sex.  Further more, according to the baby Pachyrhinosaurus skulls on the fossil record, we know they didn't have any of this dramatic headgear until much later in life, so it may have been a sexual display adaptation, or possibly for fighting fellow adults for dominance.

Pachyrhinosaurus lakustai skull on display at the Royal Belgian Institute of Natural Sciences.

As stated above, Pachyrhinosaurus is known from three different species.  The two Canadian species are called Pachyrhinosaurus canadensis and Pachyrhinosaurus lakustai.  P. lakustai is the oldest, having lived between 74 and 73 million years ago.  P. lakustai was unique in that many specimens had prominent horns growing out of the centers of their frills.  Some refer to it as the "unicorn dinosaur" because of this.  Pachyrhinosaurus canadensis is slightly younger, having lived between 72 and 71 million years ago, with a bigger nose boss.  Finally, there is the youngest species that lived all the way up in what is now Alaska, Pachyrhinosaurus perotorum, which lived between 79 and 69 million years ago, with the overall most extensive nose boss of the three species.  (There is certainly individual variation between specimens of each species. Not every individual P. perotorum had a bigger nose boss than every single P. canadensis, for instance.)

Pachyrhinosaurus is sometimes referred to as having a "unicorn horn".

Pachyrhinosaurus is a well-studied dinosaur, known from many specimens.  In fact, there were over a dozen skeletons of this dinosaur all discovered together in the same area in Alberta, Canada, called Pipestone Creek.  It is possible that the poor dinosaurs died trying to swim across a river that had flooded.  Among these specimens there were small juveniles all the way up to large adult animals.  This tells us that Pachyrhinosaurus was a dinosaur that at least sometimes lived in groups and most likely looked out for its young.

Pachyrhinosaurus canadensis at the Geological Society in Copenhagen.

When alive, Pachyrhinosaurus would have co-existed with many other dinosaurs including Edmontosaurus regalis and the tyrannosaurid, Albertosaurus.  The Alaskan Pachyrhinosaurus perotorum would have probably met Nanuqsaurus, another tyrannosaurid.

Pachyrhinosaurus belongs to a group, or subfamily, called centrosaurinae within the ceratopsian group.  Centrosaurine ceratopsids tended to have taller, thicker snouts, longer tails, and shorter frills than other large ceratopsids.  They also typically (not always) were devoid of long brow horns and instead sported large, bony structures on their snouts.  Other examples of centrosaurine ceratopsians are Styracosaurus and Sinoceratops.

That's all for this week!   Join us next week for the last prehistoric animal review of 2013!  As always feel free to comment below or on our facebook page! 

References

Anthony R. Fiorillo and Ronald S. Tykoski (2012). "A new species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope (Prince Creek Formation: Maastrichtian) of Alaska". Acta Palaeontologica Polonica 57 (3): 561–573. doi:10.4202/app.2011.0033.

C. M. Sternberg. 1947. New dinosaur from southern Alberta, representing a new family of the Ceratopsia. Geological Society America Bulletin 58:1230

Currie, P.J., Langston, W., and Tanke, D.H. (2008). "A new species of Pachyrhinosaurus (Dinosauria, Ceratopsidae) from the Upper Cretaceous of Alberta, Canada." pp. 1-108. In: Currie, P.J., Langston, W., and Tanke, D.H. 2008. A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Research Press, Ottawa, Ontario, Canada. 144 pp. ISBN 978-0-660-19819-4

E. B. Koppelhus. 2008. Palynology of the Wapiti Formation in the northwestern part of Alberta with special emphasis on a new Pachyrhinosaur bonebed. International Dinosaur Symposium in Fukui 2008: Recent Progress of the Study on Asian Dinosaurs and Paleoenvironments. Fukui Prefectural Dinosaur Museum, Fukui 65-66.

Prehistoric Beast at the Academy of Natural Sciences

I visited Philadelphia's historical natural history museum, The Academy of Natural Sciences, my first weekend after moving to this city, almost three years ago.  I also landed a job working in their education department, and regularly volunteer prepping fossils in their lab.  That being said...for some reason I never wrote a proper post about it.  Let's fix that now.

Outside of the museum.  (Photo by Ashli Lenox)

The Academy of Natural Sciences is the oldest science research institution and museum in the United States.  This is the museum where Edward Drinker Cope worked out of during the infamous Bone Wars in the late 1800s.  It's also the resting place of the first two dinosaurs to be formally described in America, Hadrosaurus and Dryptosaurus.  Needless to say, it's a special place and should be one of the top museums to visit for anyone who likes paleontology or American history.

This awesome life-sized statue of two running Deinonychus, sculpted by Kend Ullberg, was erected in front of the museum in the 1980s.  At the time this was an extremely up-to-date depiction, especially since the idea of light, fast-moving dinosaurs was still novel.  (photo by Ashli Lenox)

When you first walk in the front doors, you are greeted by the skeleton of the giant marine reptile, Elasmosaurus, swimming at you from the ceiling.  This creature has more significance than just looking cool, however.  It was this Elasmosaurus that in some ways started the Bone Wars, the historical event when Othniel Marsh embarrassed fellow paleontologist, Edward Drinker Cope, by pointing out during Cope's debut of this skeleton, that the skull was put on the tip of the tail, instead of the neck.

In the back of the front lobby is a cast and 3D life reconstruction of Tiktaalik, a fossil that helped prove the evolutionary connection between fish and land vertebrates.  The actual fossil of Tiktaalik is currently in Northern Canada, where it was discovered, but it was brought to the Academy of Natural Sciences to be studied and published.

Tiktaalik cast and life reconstruction. (photo by Ashli Lenox)

When you first enter the Academy's fossil hall, you are attacked by a lunging Tyrannoaurus skeleton.  This is a cast of the same T. rex skeleton on display at The American Museum of Natural History, in New York, affectionately referred to by its ID number, 5027.

The T. rex is the central attraction in the Acdemy's fossil hall.  The scapula (shoulder blades where the arms attach) are erected too close together.

Right next to Tyrannosaurus, is a medley of other meat-eating dinosaur skulls, including Acrocanthosaurus, Majungasaurus, Dilophosaurus, Velociraptor, Herrerasaurus, and Eoraptor.  Lots of people come into the museum asking to see a Velociraptor, then get really disappointed when they are shown the actual skull and see how small their favorite Jurassic Park monster really was.  Luckily for those folks, we have a lovely mount of the larger dromaeosaurid, Deinonychus, in all its predatory glory, attacking a family of Tenontosaurus.

Meat-eating dinosaur skulls that are not T. rex!

While we're on the subject of Jurassic Park, the Academy of Natural Sciences showcases almost all of the main dinosaurs featured in the beloved franchise.  This is actually really cool from an educational standpoint because educators giving tours can show visitors the dinosaurs they are already somewhat familiar with and therefore, more effectively implement the real science behind them.  Not sure if having all these specific dinosaurs was on purpose, but it's convenient.

Deinonychus attacking a family of Tenontosaurus.

Another notable skeleton on display is that of the crested hadrosaurid, Corythosaurus.  It's a massive specimen, towering over almost everything else in the room, flanked by the ceratopsian, Chasmosaurus, with two Pteranodon skeletons suspended near its head.  What I really like about this display, is that the Corythosaurus mount is almost all the original fossil bones, not casts.  The only exception is the skull, which is a lightweight cast since the real one was too heavy to be safely mounted up that high.

Corythosaurus

The main fossil hall has a fair share of marine fossils.  Most impressive, in my opinion is a beautifully preserved Ichthyosaurus that spent over one hundred years at the Academy, mostly in the behind the scenes collections.  Only very recently, in 2016, it was realized, upon closer examination, that this specimen was a previously unnamed species.  It was given the full name Ichthyosaurus somersetensis, and is now on full display in the main fossil hall.

Ichthyosaurus somersetensis

The Academy of Natural Sciences has a fossil prep lab, where paleontologists and  volunteers work on cleaning off and assembling pieces of dinosaur bones collected every summer in Montana.  Most of the fossils that are currently being worked on are from the Late Jurassic Morrison Formation.  The sauropod dinosaur, Suuwassia, was discovered, prepped, studied, and scientifically described by folks from the Academy of Natural Sciences.  A glass case with a few bones from this amazing dinosaur is on display right next to the lab.  Visitors can walk right in, look at the specimens currently being prepped, and talk to /ask questions of the scientists and volunteers as they work.

Neck vertebrae of Suuwassia on display in the Academy's fossil lab.  There are more bones from this dinosaur in the museum's collections, and even more in the lab that have yet to be prepped.  We are learning more about this relatively newly discovered dinosaur every day.

Finally, I'd like to share what I am most impressed by at this museum, the first and second American dinosaurs ever described by science! (and they're both from my home state, New Jersey!) Hadrosaurus and Dryptosaurus are both on display at the Academy.  Casts of Dryptosaurus' bones are in a glass case in the main fossil hall, across from a wall mount of casts of the known skeleton of New Jersey's official state fossil, Hadrosaurus foulkii.  On the second floor, however, there is a full skeletal mount of Hadrosaurus on display.  The unknown bones of this skeleton are filled in with the bones of more completely known hadrosaurid dinosaurs, like Maiasaura.  Not only does the Academy have these two important dinosaurs on display, it is also the housing place of their real bones down below in its collections drawers.

Casts of  some of the bones of Dryptosaurus on display in the fossil hall.

Known skeletal elements of Hadrosaurus are mounted in the museum's fossil hall.

On the second floor there is a full skeleton of Hadrosaurus, supplemented with bones from other related dinosaurs to fill in the gaps.  Because of this, the right femur (from a Maiasaura) is longer than the left one (from Hadrosaurus)

There are lots of fossils on display that I did not include in this post.  In addition, there are many other exhibits, other than the fossil hall, that are worth seeing at the Academy.  If you are ever in the Philadelphia area, make sure to go see for yourself!  Stay tuned for part two of my tour of the Academy of Natural Sciences, where we will take a look behind the scenes and see fossils that you don't get to see on a regular visit!

Macrocollum: Prehistoric Beast of the Week

This week we will be checking out a newly discovered dinosaur that is currently the oldest known member of its family. Check out Macrocollum itaquii!

Macrocollum was a plant-eating dinosaur that lived in what is now Brazil, during the late Triassic period, about 225 million years ago.  When alive, it would have measured about sixteen feet long from snout to tail.  The genus name translates from Greek to "long neck".

Macrocollum life reconstruction in watercolors by Christopher DiPiazza.

Macrocollum is an important find because it is the oldest known member of the group of dinosaurs known as the basal sauropodomorphs, or "prosaurpopods" as they have also been called.  These dinosaurs were common during the late Triassic and early Jurassic and are characterized by having long necks and tails, and proportionally small heads.  Many of them walked on their hind legs primarily, but others could also have dropped down to all fours, as well.  Plateosaurus, Massospondylus, Mussaurus, and Ingentia, are also members of this group.  There is evidence to suggest that this group of dinosaurs would later give rise to the gigantic sauropods, like Brontosaurus and Apatosaurus.

Close up photograph of a Macrocollum skull.  Note the down-turned tip of the snout and the small, leaf-shaped teeth.

The fact that Macrocollum is from as old a time as it is, combined with its anatomy, is what makes it extremely interesting, and tells us a lot about sauropodomorph evolution.  Macrocollum had a very long neck, and proportionally small head, just like later members of its family.  This tells us that, since it is so far the oldest-known member, that the sauropodomorph body type must have happened even earlier, from an ancestor that didn't have a long neck and proportionally small head.  Many paleontologists agree that the common ancestor to dinosaurs was a meat-eater.  Macrocollum's proportionally small head, small, leaf-shaped teeth, and long neck are all adaptations for eating plants, which proves that being a plant-eater must have evolved much earlier in the dinosaur family tree, too.

Multiple skeletons of Macrocollum were discovered very close to each other.  Each individual animal's remains are highlighted in a different color.  Image from Federal University of Santa Maria.

Macrocollum is also interesting in that multiple individual skeletons were discovered nearby each other.  This suggest that this dinosaur may have been social, perhaps living in groups, or sticking with family members as an adult, which is exciting to think about and rarely supported by fossil evidence.  That being said, keep in mind it is also possible that these dinosaurs may have just congregated at a riverbed in search of a resource, like water, during a time of drought, and all died at about the same time from lack of that resource.

References

Rodrigo Temp Müller; Max Cardoso Langer; Sérgio Dias-da-Silva (2018). "An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs". Biology Letters. 14 (11)