M is for Mojoceratops

Moving on to the letter 'M', we welcome another ceratopsian (horned) dinosaur to our Alberta dinosaurian alphabet with Mojoceratops. 

Mojoceratops has an interesting history, and invokes discussion of a common problem in palaeontology that we deal with constantly. As is often the case, Mojoceratops is known from partial remains, and in this case, it is known from several skull pieces, representing nearly an entire skull. First, Lambe found a partial skull, which he called "Eoceratops canadensis" in 1915 [1]. Unfortunately, this was based on a skull with no descriptive characters, and furthermore, is a juvenile. A few years later, Brown found another partial skull and named it "Chasmosaurus kaiseni", again from partial remains with few descriptive characters (albeit more than E. canadensis) [2]. Even more difficult, a further specimen was named "Chasmosaurus canadensis". This specimen is the type specimen, of the species Mojoceratops perifania named by Nick Longrich in 2010, along with the previously mentioned specimens and other new specimens [3]. You might think the name is a bit funny, and you would be right. First of all, genus and species names are almost always derived from Latin or Greek, and 'mojo' is neither: it's derived from "20th century African-American English" [3]. Furthermore, it means just what you think it means. Longrich describes a mojo as "a magic charm or talisman often used to attract members of the opposite sex", referring to its large frill that may have been used in courtship. He distinguishes it from Chasmosaurus because it lacks a forward-curving process on the frill and reduced postorbital horns found in Chasmosaurus. Currently recognised specimens come mainly from southern Alberta in the Dinosaur Park Formation, while some may be found in southern Saskatchewan as well. The fossils come from the Late Cretaceous, about 75 million years ago. 

Artists impression of Mojoceratops perifania by Nobu Tamura. Note the large frill and orbital horns.

The complicated history of Mojoceratops makes it a somewhat controversial taxon. It does seem to be recognised as separate from Chasmosaurus, because it lacks specific features found in Chasmosaurus (like the curved processes and short orbital horns). However, the rules of zoological nomenclature are clear: the name that was first given to an animal takes precedent over any other name given to it, unless there is a valid reason not to. In the case of "Eoceratops canadensis", its non-descriptive and juvenile nature provide a good reason NOT to use this as a name. Moving to "Chasmosaurus kaiseni" provides us with another challenge. It is recognisably different from Chasmosaurus, and therefore should be given a new generic (as in the first name in species). Normally in these cases, a new generic name is erected, while the specific epithet ("kaiseni") is kept, to recognise the original name. However, Longrich chose to erect both a new generic and specific name. In one study, they refer to it as Mojoceratops kaiseni, recognising the original specific name [4]. This is often a problem in palaeontology, especially when looking at fossils that were found in the early 1900's. Making this species even more controversial, a recent study questioned its distinctiveness from Chasmosaurus [4]. 

In general, it's a bit of a mess, but it is currently recognised as a valid taxon. Hopefully this has given you a bit of insight into the complicated nature of naming fossils, and the struggles that follow.  Next week we'll carry on with the letter 'N', with an armoured dinosaur! 

Other 'M' dinosaurs found in Alberta:
Monoclonius (also a controversial ceratopsian)
Montanaceratops - a ceratopsian 

References
1 Lambe, L. 1915. On Eotriceratops canadensis, gen. nov., with remarks on other genera of Cretaceous horned dinosaurs. Canada Geological Survey, Museum Bulletin 12: 1-49.
2 Brown, B. 1933. A new longhorned Belly River ceratopsian. American Museum Novitates 669: 1-3.
3 Longrich, N.R. 2010. Mojoceratops perifania, a new chasmosaurine ceratopsid from the late Campanian of western Canada. Journal of Paleontology 84: 681-694.
4. Mallon, J.C., et al. 2011. Variation in the skull of Anchiceratops (Dinosauria, Ceratopsidae) from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta

L is for Lambeosaurus

Next up in our Albertan dinosaurian alphabet is 'L is for Lambeosaurus'. Lambeosaurus is another duck-billed dinosaur, or hadrosaur, from southern Alberta. Unlike last week's hadrosaur Kritosaurus, Lambeosaurus is known from many fossils and is very well known. 

Lambeosaurus was first named in 1923, despite some poorly preserved fossils being found and described about 20 years earlier by well-known Canadian palaeontologist Lawrence Lambe, which is where the name comes from. In fact, the type species is called Lambeosaurus lambei, with both the genus and specific epithet honouring for Lambe. It lived during the Late Cretaceous, about 75 million years ago. To repeat what I've said many times before about hadrosaurs, like others, it was capable of walking on two or four legs, or as we say, it was a 'facultative biped', which means it was capable of either. It was also a herbivore, and used its large 'battery' of teeth to grind down tough vegetation, and had a cheek-like structure that allowed it to chew its food. Another similarity to other hadrosaurs that I haven't mentioned previously is that it had 'ossified tendons' in its tail, which means the tendons were strengthened to keep the tail stiff. Lambeosaurus is also the type species for the group of hadrosaurs that typically have large, hollow cranial crests (the Lambeosaurinae), and it is no exception. These crests have a nasal cavity that runs through it, making it hollow, and was likely used to make noise for species recognition or social uses [1]. This is also supported by the fact that the crests are only present in adult individuals, and are not found in juveniles. 

Artists impression of Lambeosaurus magnicristatus showing the large cranial crest

Currently, only two species of Lambeosaurus are recognised, and they have only been found in Alberta. They are differentiated primarily by their crest. L. magnicristatus, as seen above, has an expanded blade-like crest, like a pompadour, while L. lambei has a thinner blade, and is described as a hatchet-like crest (as seen below). Lambeosaurus was about 9 metres in length, and 4 metres tall when standing on all fours. At one point, there were many species recognised, and several other species of smaller hadrosaurs were thought to be separate species. However, a re-evaluation of the groups showed that the smaller ones were actually juvenile Lambeosaurus, while other differences between species were thought to be sexual dimorphism [2,3]. 

Artists impression of possible growth stages and male/female variation within Lambeosaurus. Image by Nobu Tamura 

Both currently recognised species of Lambeosaurus are found in the Dinosaur Park Formation of southern Alberta. Other dinosaurs that live in this formation include ceratopsians (e.g. Centrosaurus and Styracosaurus, hadrosaurs (e.g. Corythosaurus and Parasaurolophus) and the theropod Gorgosaurus. This rock formation represents a highly diverse, and very well documented Late Cretaceous ecosystem, thought to be from a low-lying area with swamps, rivers, an floodplains [4]. 

That's it for Lambeosaurus! Next week, we'll talk about a ceratopsian dinosaur from southern Alberta. 

Other dinosaurs from Alberta that start with 'L':
Leptoceratops

References
1. Horner, J. R. et al. 2004. Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmolska, H. (eds) The Dinosauria (2nd edition). Berkeley: University of California Press pp. 438-463.
2. Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine dinosaurs. Systematic Zoology 24: 37-54.
3. Horner, J.R. 1979. Upper Cretaceous dinosaurs from the Bearpaw Shale (marine) of south-central Montana with a checklist of Upper Cretaceous dinosaur remains from marine sediments in North America. Journal of Paleontology 53: 566-577.
4. Eberth, D.A. The geology. Dinosaur Provincial Park. Indiana University Press, Bloomington (2005): 54-82.

K is for Kritosaurus

This week, we're back to dinosaurs from Alberta, with 'K is for Kritosaurus'. Kritosaurus was a hadrosaur (duck-billed) dinosaur from the Late Cretaceous (about 73 million years ago) of North America, including southern Alberta, New Mexico, and Texas. It is recognised by a crest in front of its eyes, but the exact form of this crest is unknown. It was similar to other hadrosaurs in size, at about 8 m long, walked on two or four legs, and like all hadrosaurs, it was a herbivore. It used its large battery of flat teeth to grind down tough plant material. The teeth were constantly replaced, unlike mammals which have only two sets of teeth. Unfortunately, its known from very partial remains, which has made its taxonomic affinities debatable. In the past, Kritosaurus has been synonymised with Gryposaurus and Hadrosaurus, but is currently considered to be a valid genus. 

Kritosaurus by Nobu Tamura

Kritosaurus was first discovered in the US, in a formation alongside other dinosaurs like the hadrosaur Parasaurolophus, the ceratopsian Pentaceratops, and theropod Saurornitholestes. The nasal crest may have been used for social displays. 

Kritosaurus is actually the only dinosaur that starts with 'K'  from Alberta. Next week, we'll talk about another hadrosaur (I know, there's a lot of hadrosaurs from Alberta!) with a neat crest.

J is for Juravenator

Continuing on with our alphabet, we come to J. Unfortunately, there are no dinosaurs from Alberta that start with the letter 'J', so we bring you 'J is for Juravenator', which is a small theropod from Germany.

Juravenator is known from a single specimen found in southern Germany, and lived during the Late Jurassic, approximately 151 million years ago. Although it is only known from one specimen, this specimen is extremely well preserved and almost entirely complete. First discovered in 1998, it had an interesting past. It was very difficult to prepare, as the surrounding rocks are very tough and the bones are fragile, and at one point it was abandoned, thought to not be worth it. After gaining press from 1999-2001, it was finally looked at again in 2003 when they discovered a nearly complete dinosaur, which was named in 2006 [1]. The name means 'Jura-hunter', where Jura signifies that it was found in the Bavarian Jura mountains. The fossil was found in layered limestone from the Solnhofen region of Germany, typified by very fine-grained sediments. This area is known for the beautiful preservation of fossils due to the quiet lagoon-type setting these animals died in. 

Image of Juravenator from Goehlich and Chiappe [1]

The single specimen of Juravenator is a juvenile, known by the lack of fusion between bones and still-open sutures in the vertebrae [1]. Like other small theropods, it was a bipedal carnivore, and was less than a metre in length (but remember, it's just a juvenile!). The initial description found that Juravenator had no evidence of feathers or integumentary covering, which was interesting considering it was thought to be closely related and nested within many dinosaurs known to have filamentous coverings [1]. However, a re-examination of the fossil in 2010 revealed (through the use of ultra-violet light) that the animal actually had many small filaments covering various parts of the body, which is similar to other closely related coelurosaurs like Sinosauropteryx [2]. These filaments are thought to be 'primitive feathers' and can be found in many theropod dinosaurs. Another interesting thing about Juravenator is that it also shows evidence of scales, which is highly unusual as scales and filaments are rarely found together [2]. Of further interest, it happens to be one of the most complete non-avian (as in not a bird) theropod skeletons to be found in Europe!

Hopefully you enjoyed learning about the small theropod Juravenator. You can learn more about this little dino from Brian Switek's post, since we independently came up with the same guy for our features! Next week, we'll be back to dinosaurs from Alberta for our dinosaurian alphabet, with the letter 'K'!

References:
1. Goehlich, U.B., and Chiappe, L.M. 2006. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago. Nature 440: 329-332.
2. Chiappe, L.M., and Goehlich, U.B. 2010. Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany. Neues Jahrbuch fuer Geologie und Palaeontologie - Abhandlungen 258: 257-296.

I is for Irenesauripus and Ichnofossils!

This week we are going to do something a little bit different for the Alberta Dinosaurian Alphabet. This week, we have 'I is for Irenesauripus, and ichnofossils!

Irenesauripus is a type of ichnogenus, also known as a trace fossil or ichnofossil. Specifically, it is a kind of dinosaur footprint from the Cretaceous of North America. It was first discovered in the 1930's in Peace River, British Columbia, but has since been recorded in Alberta, the Yukon, and Texas. Albertan Irenesauripus tracks are typically found in the area of Grand Cache. These fossils are all three-toed and found in trackways. They represent an animal that walked on two legs (bipedal), walked on its toes (digits) rather than flat-footed, and had widely spaced impressions of the toes. They have evenly distributed weight, and show evidence of claws on each toe. In the original description, it was described as a theropod, and several studies have since agreed [1-3] while one has even gone further in declaring it a member of the Megalosauroidea [4]. These prints represent large theropods, as they are typically 28-40 cm in length. 

Example of Irenesauripus from Richard McCrea

As mentioned before, 'I' is also for ichnofossils, and ichnology. Ichnology is the study of trace fossils, which includes anything other than actual remains of animals, but rather they show behaviour. These include trackways or footprints, burrows, or even coprolites (fossilised feces). The great thing about trace fossils is that they can give us direct evidence of behaviour, which traditional fossils (like bones) typically do not. For example, a large number of trackways showing several different kinds of tracks can show a herbivore being attacked by carnivores. Or, a number of tracks from the same type of animal can show that they travelled in a herd or pack. Fossilised burrows can show us how an extinct animal made its burrow and how it lived. Unfortunately, more often than not, it is very difficult to associate a trace fossil with a specific animal. We can make assumptions based on the size of fossil and the animals that we know were around at the right time, but there is often no way we know for sure what animal made the tracks. This is why trace fossils are called ichnospecies rather than species, because they do not necessarily represent an entirely new species. Irenesauripus was a theropodian ichnogenus that would have represented a large theropod because of the size of print as well as stride (about 1 m in length). 

That's it for this week. Hopefully we introduced you to another side of palaeontology that you may not have thought about before, as well as a new area in Alberta where dinosaur fossils can be found! Stay tuned for 'J' next week, which unfortunately will be from outside of Alberta. 

Other 'I' dinosaurs from Alberta:
Ichthyornis - a bird (remember, birds technically are dinosaurs!)

References:
1. Kuhn, O. 1963. Pars 101. Ichnia Tetrapodorum. In F. Westphal (ed.), Fossilium Catalogus. I: Animalia. Ysel Press, Deventer, Netherlands. 176 pages
2. M. G. Lockley. 1992. Cretaceous dinosaur-dominated footprints assemblages: their stratigraphic and palaeoecological potential. In N.J. Mateer & P.-J. Chen (eds.) Aspects of Cretaceous Geology. China Ocean Press, Beijing, 269-282.
3. Gangloff, R. A., et al. 2004. An early Late Cretaceous dinosaur tracksite in central Yukon Territory, Canada. Ichnos 11: 299-309.
4. Haubold, H. 1971. In O. Kuhn (ed.) Handbuch der Palaeoherpetologie. Part 18. Ichnia Amphibiorum et Reptiliorum Fossilium. Gistav Fischer Verlag, Stuttgart. 1-124.

H is for Hesperonychus

Next up in our Alberta dinosaurian alphabet is Hesperonychus, a small theropod. Its name means 'western claw', in reference to the sickle-shaped claw it has on both hindlimbs. This claw tells us that it was a dromaeosaur, commonly referred to in popular media as the 'raptors' like Velociraptor or Deinonychus. It lived during the Late Cretaceous period of southern Alberta, approximately 75 million years ago. These fossils were collected in 1982, and were left undescribed and virtually ignored until they were re-discovered by Nick Longrich and Phil Currie in 2009 [1].

Artists impression of Hesperonychus by Nobu Tamura

Although known from only a few bones, the estimated total length of Hesperonychus is less than 1 m, and it weighed as little as 1.9 kg [1]. Due to the degree of fusion in the bones, it's likely this is in fact a full-grown adult individual, making it one of the smallest theropod dinosaurs found in North America, second only to Albertonykus. 

Hesperonychus is the first microraptorine dinosaur found in North America, and it is also one of the few small theropods, which is significant ecologically. Previously, the ecosystems of the Late Cretaceous of North America lacked small theropods (we couldn't find their fossils), while similarly aged environments in Europe and Asia had several. This find helped to fill this gap rather than having to develop an explanation for why these small animals didn't exist in North America. We now understand that carnivorous dinosaurs in North America ranged from very tiny (Hesperonychus) to very large (e.g. Tyrannosaurus rex) [1]. It is even likely that this small theropod was very common throughout Cretaceous Alberta. Although few bones are easily distinguishable as Hesperonychus, there are several small claws within collections of museums that likely represent claws from this animal. Unfortunately, claws are not very distinct between species and it can be hard to determine exactly what animal it comes from. For a bit more about this find, you can view articles from CBC and BBC. 

That's really all that is known from this small carnivorous theropod. Next week, we're going to talk about something a little bit different: dinosaur trackways!

Other dinosaurs from Alberta that start with 'H':
"Hadrosaurus" - although this isn't necessarily considered to be a valid name by all palaeontologists
"Hanssuesia" - synonym of the pachycephalosaur Stegoceras
Hypacrosaurus

References:
1 Longrich, NR, and Currie, PJ. 2009. A microraptorine (Dinosauria-Dromaeosauridae) from the Late Cretaceous of North America. PNAS 106: 5002-5007. Not open access but can be viewed here.

G is for Gryposaurus

Now that the holidays are over, we're back to our current feature: the Albertan dinosaur alphabet. Back before the holidays started, you'll remember we talked about the strange dinosaur Falcarius, which is not from Alberta. Now, we're back with a duck-billed dinosaur from Alberta called Gryposaurus.

Gryposaurus (pronounced 'GRYE-puh-SAWR-us') means 'hooked-nose lizard' and was a duck-billed (hadrosaur) dinosaur that lived 83-75 million years ago in North America. Its remains have been found in Montana, Utah, and Alberta. Its most distinctive feature is its large, arching, humped nose which distinguishes it from other hadrosaurs. It was 8-9 m long, which is pretty typical for duck-billed dinosaurs. Almost the entire skeleton is known, making it a good dinosaur to use in comparison to other lesser-known animals. 

The head of Gryposaurus showing the nasal hump. Image by Wikimedia Commons user ArthurWeasley.

The first specimen of Gryposaurus was collected along the Red Deer River in Alberta in 1913, and it has been controversial ever since. Several people have suggested that it is the same as another dinosaur called Kritosaurus (which we will discuss for the letter K), and also the very poorly known Hadrosaurus. These three dinosaurs are considered to be distinct animals, at least for now. Three species of Gryposaurus are recognised: G. notabilis (the original species named by Lambe in 1914), G. latidens (named by Jack Horner in 1992), and G. monumentensis (named in 2007).

Like other hadrosaurs, Gryposaurus was capable of walking on 2 or 4 legs, and was a herbivore. It used its hundreds of flat teeth to grind tough vegetation, and had a cheek to allow for chewing. The function of the nasal hump is not entirely known, but was likely used for social functions like sex recognition. Many hadrosaurs have nasal or cranial ornamentation for a variety of functions, and Gryposaurus is no different! 

Stay tuned next week when we move on to 'H' and a small theropod dinosaur!

Other 'G' Dinosaurs from Alberta:
Gorgosaurus
Gravitholus
Gryphoceratops