Canadian Fossils

In one week, we celebrate Canada's 146th birthday. To celebrate, we will talk about some of the different fossil sites in the country. From west to east, here are some of them:

British Columbia
The Burgess Shale is one of the most famous fossil localities in the world. Located in Yoho National Park in the Rocky Mountains of British Columbia, this geologic formation dates back to the Cambrian, approximately 505 million years ago. The Burgess Shale was made famous by its exceptional preservation of soft body parts, which are not always well preserved. The Cambrian is the first geologic period that has significant numbers of clear animal fossils in it, and is often referred to as the Cambrian Explosion. Because of this, the Burgess Shale is particularly important in terms of early evolution of many animal groups. 

The Burgess Shale was first discovered in 1909, and has been well studied ever since. It is included in the Canadian Rocky Mountain Parks UNESCO World Heritage site, named in 1984. Because of the significance of this fossil site, it is very difficult to collect from or visit this location, with visitors only allowed on guided tours. It was deposited in an ocean setting, so all fossils are marine. There have been some well known fossils discovered here, like Marella (an early arthropod), Anomalocaris (an early arthropod relative), Hallucigenia (a bizarre spiny creature) and Pikaia (a possible early chordate, a group that includes vertebrates). 

Example of sizes of different organisms in the Burgess Shale. Image by Matt Martyniuk

Alberta
There are several excellent fossil sites in Alberta which we have discussed previously on this blog. For more information on those, check out our Palaeontology in Alberta post! 

Ontario
The Gunflint Chert in Ontario (and also in Minnesota) is an iron formation that was deposited about 1.9 BILLION years ago. In these rocks are tiny microfossils from stromatolites. These rocks were first studied in the 1950s and 60s and small spheres, rods, and filaments were determined to be single-celled organisms. This find kicked off the search for Precambrian microfossils.

Nova Scotia
The Joggins Fossil Cliffs of Nova Scotia are a famous Carboniferous fossil site from about 310 million years ago. The Carboniferous is often referred to as the 'Coal Age' due to the large number of fossilised trees that have been turned into coal. In particular, Joggins has a large number of complete and even upright trees that have been preserved, especially from the lycopodiphyte Sigillaria. In 1852, a great discovery was made when geologists found tetrapod fossils within an upright tree stem. The internal part of the tree had been eroded away, while the external bark was still in place, leaving a large hole for small animal bones to fall into and become fossilised. Further investigation revealed the earliest sauropsid (the group of amniotes that include reptiles, birds, dinosaurs and more) fossil ever found, Hylonomus. Other important fossils from Joggins Fossil Cliffs include Protoclepsydrops, an early synapsid that is older than Hylonomus, and small tetrapod trackways. 

Artists impression of Hylonomus by Nobumichi Tamura

Newfoundland and Labrador
Mistaken Point is found on a peninsula on the island of Newfoundland, and contains more Precambrian fossils, including some of the most diverse and well-preserved fossils from this time.  It contains what is most likely the oldest multi-cellular fossils from North America, the oldest deep water fossils and the oldest Ediacaran fossils in the world. They date back 575-560 million years. 

Nunavut
Although there aren't any truly fossiliferous sites in Nunavut, at least not like the ones we have mentioned previously, it is home to one of the most famous and important fossils ever discovered. In 2004, a group of palaeontologists discovered a partial skull sticking out of a cliff on Ellesmere Island. When they analysed it, they discovered it was an early tetrapod. This fossil, called Tiktaalik from the Devonian (375 million years ago), is an example of what we call a transition fossil. It shows the transition that palaeontologists refer to as "from fish to limbs". It's also what palaeontologists sometimes call a 'fish-er-pod', as in it has a combination of fish (e.g. gills and fins) and tetrapod (e.g. mobile neck and lungs) characteristics, as well as transitional features (e.g. half-fish, half-tetrapod limb bones and joints). Although there is only one of these fossils known, it has been extremely important in understanding the evolution of early tetrapods.

Artist's impression of Tiktaalik by Nobumichi Tamura

Although we only talked about a few localities, there are fossil localities all over the country, and in every province and territory! Unfortunately, if we talked about all of them, we would be hear for a while... So we hope you enjoyed these few examples of Canadian fossil localities. And have a great Canada Day next week! We will be open everyday next weekend from 9-7, and will have activities and special guests throughout the weekend. Visit our website for more details!

Colour in Fossils

Dinosaurs are always displayed as colourful, but how do we know what colour they were? The truth is, in most cases, we don't. In the typical depictions of scaly, reptilian dinosaurs, we can make educated guesses based on animals today, and the habitat of the dinosaur in question. For example, herbivorous animals that would need to hide from predators wouldn't be brightly coloured: they would be dull, earthy colours to allow them to fade into the background and hide from predators. Features that are used for some kind of display, like a crest, would likely have been brightly coloured, as it allows an even greater display. 

Caulkicephalus, a pterosaur from England illustrated with a bright blue and yellow crest. Copyright of Mark Witton

More recently, a new way of telling fossil colouration has been discovered. There are several forms of pigment in animals today, including melanin, carotenoids, luciferin, and more. Melanin is found in little packets called melanosomes, and is responsible for brown, black, and red colouration. These packets come in different shapes, for different colours. Eumelanin, responsible for brown-black colouring, is found in elongate sausage-shaped melanosomes, whereas pheomelanin, responsible for red or ginger colouring, is found in spherical melanosomes. They are very small structures, and can be seen using a Scanning Electron Microscope (SEM). This was first used in a fossil feather from the Lower Cretaceous [1], while the theropod Sinosauropteryx was the first dinosaur to have its colouration described by looking at melanosomes. The fossils showed a strange banding of the primitive feathers in a dark, and light pattern. When these different sections were analysed under SEM, pheomelanosomes were discovered in the darker banded areas, and no melanosomes (i.e. no pigment, and therefore white) were found in the lighter areas [2]. The authors suggested that to mean this animal had a tail banded in white and reddish colours in life. 

Since that first feathered dinosaur discovery, several other extinct feathered animals have been analysed using this method. This includes the four winged dinosaur Microraptor, and the possible early bird Anchiornis. In fact, one study on Microraptor has actually suggested that you can see iridescence from looking at the pattern of melanosomes within the fossils.

Artists impression of Anchiornis, colouration patterns known from fossilised feathers. Image by Nobuyuki Tamura.

 For anyone interested in more information about colouration in fossils and feathers, check out the blog Prehistoric Colours by a group at the University of Bristol in the UK. They are currently working on this issue and looking at different pigments found in fossils and how you can identify them. They are also working on identifying deformation in these structures in the fossil record. It's really neat research!

References:
1. Vinter, J., et al. 2008. The colour of fossil feathers. Biology Letters 4: 522-525.
2. Zhang, F., et al. 2010. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature 463: 1075-1078.

Birds are Dinosaurs!

Did you know that birds are actually dinosaurs? 

This point is briefly mentioned in one of the very first Mesozoic Mondays post on saurischian dinosaurs, but little information on the subject is given. Here, I'm going to give a brief overview of the idea, what it means, and some of the evidence we have. 

The similarity between reptile skeletons and birds was noticed as early as the 1800s, with Thomas Huxley (one of the initial proponents of evolutionary theory) pointing out that the early bird Archaeopteryx showed transitional features between the two groups. He compared this fossil to dinosaurs that were known at the time, like Compsognathus, in great detail. However, his ideas were not widely accepted at the time. In the early 1900s, the issue was reviewed again, with Gerhard Heilmann (a Danish scientist) again concluding that theropod dinosaurs showed the most similarity to Archaeopteryx and other birds. However, no clavicles (collar bones) were known from dinosaur fossils, which in his mind meant that they could not be related as birds possess a fused clavicle called the furcula (or wishbone). Although the absence of clavicles does not rule out a relationship between the two (features can be lost and gained throughout evolution), we now know that theropods and possibly all saurischian dinosaurs did indeed possess a clavicle. The debate came around again in the 1960s when famous American palaeontologist John Ostrom named the dromaeosaur Deinonychus, and he noticed the similarities again between it and Archaeopteryx. Ostrom solidified the theory in palaeontology, and brought it to the front as the leading theory on the origin of birds.

Comparison of the hands and wrists of Deinonychus (left) and Archaeopteryx (right) shows the similarities between these two. Image copyright John Conway

Although there were major morphological similarities, there was still the major question of feathers. If Archaeopteryx, an early bird, showed fully developed flight feathers, where did they come from? Features do not just appear in animals fully formed: they need to evolve slowly and gradually. Finally, in the 1990's, several amazingly preserved bird fossils from the Early Cretaceous were found in a region of China, and in 1996, the first 'feathered' dinosaur was described. Sinosauropteryx was initially described as a bird (hence the -pteryx portion of the name, which means wing) [1]. Shortly after, however, its similarity to dinosaurs was discovered, and the importance of the fossil fully understood [2]. Although the skeleton itself is not remarkable in terms of dinosaurian anatomy, it is covered in tiny hair-like filaments from the head to to the tail. These filaments are thought to be 'protofeathers', an early evolutionary stage of feathers. 

Artists impression of Sinosauropteryx by Nobu Tamura. Note the patterned tail

Since Sinosauropteryx, numerous theropod dinosaur fossils have been found with filamentous feathers, mainly from China. These include Caudipteryx which has a cool tail fan, Velociraptor, Yutyrannus (an early tyrannosaur) and Microraptor, an odd 4-winged creature that may have been capable of flying, although this is debated. This means that more and more dinosaurs likely had some kind of feathers or filamentous covering, rather than the scaly appearance we see in the media. Look out for feathered T. rex in any scientifically accurate dinosaur portrayals! There is even some evidence that Psittacosaurus, an early relative of horned dinosaurs had some quills derived from early feathers, although this is controversial [3]. In addition to clarifying the story of bird evolution, these feathers can be useful in understanding colouration of these animals as well. Small structures called melanosomes, which house the colouration pigment melanin, can be preserved. This is where the striped pattern of the tail of Sinosauropteryx comes from. This will be described in more detail next week. 

Although the vast majority of palaeontologists now recognise the dinosaurian origin of birds, like all theories, there are a few holdouts that do not accept it. However, the evidence is overwhelming, and each issue that is brought forth by these people has been countered with fossil or developmental evidence. 

So what does this all mean? Birds are dinosaurs! As birds are directly descended from a group of theropod dinosaurs (the deinonychosaurs), they are considered to be dinosaurs in biological terms. Much in the same way that whales are mammals, as they share numerous characters with mammals, and evolved from terrestrial mammals, millions of years ago. 

I know this was a bit brief, but bird evolution is a topic we could talk about for hours. If you're interested in more, there are numerous websites that cover this topic in more detail!

References:

1. Ji, Q. and Ji, S. 1996. On the discovery of the earliest bird fossil in China (Sinosauropteryx gen. nov.) and the origin of birds. Chinese Geology 233: 30-33. 

2. Chen, P. et al.  1998. An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China. Nature 391: 147-152.

3. Mayr, G. et al. 2002. Britle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus. Naturwissenschaften 89: 361-365.

Z is for Zupaysaurus

After 26 long weeks, we are now at the final dinosaur from our dinosaurian alphabet! This week, we bring you 'Z is for Zupaysaurus', a theropod from Argentina.

Zupaysaurus lived during the Late Triassic period, about 215 million years ago in northern Argentina. The name comes from the local Quechua word 'zupay' meaning devil. It was a medium-sized bipedal theropod, between 3 and 4 m in length, and weighed about 200 kg. It is known from one definitive specimen, which includes a nearly complete skull, vertebrae, and incomplete arms and legs [1]. In the original description, it was thought to have two parallel cranial crests, like those seen in Dilophosaurus. However, more recent analysis has suggested that these "crests" were simply bones that had been pushed up during deformation of the skull [2]. 

Artists impression of Zupaysaurus by FunkMonk

Like most theropods, Zupaysaurus was a carnivore. Most analyses suggest that it was a coelophysoid dinosaur, being closely related to the Antarctic theropod Cryolophosaurus, and was the first coelophysoid to be found in South America. It was found in the Los Colorados Formation of Argentina, which is thought to have been a floodplain. This formation is home to many sauropodomorph dinosaurs, like Riojasaurus, and many other tetrapods such as therapsids, pseudosuchians, and other archosaurs. In fact, it is one of the earliest known animal fossil assemblages that was dominated by dinosaurs!

And that is it for our dinosaurian alphabet! I hope everyone has enjoyed it. I'm looking for ideas of what to do for the blog in the future, so if anyone has anything they'd like to learn about, please let me know!

References
1. Arcucci, A. B., and Coria, R. A. 2003. A new Triassic carnivorous dinosaur from Argentina. Ameghiniana 40: 217-228. 
2. Ezcurra, M. C., and Novas, F. E. 2007. Phylogenetic relationships of the Triassic theropod Zupaysaurus rougieri from NW Argentina. Historical Biology 19: 35-72.

Y is for Yulong

Last week was our last dinosaur that was actually from Alberta. Now our second last dinosaur of the dinosaurian alphabet is a newly described theropod from China: Yulong. 

Yulong was described at the beginning of this year by a group of Chinese palaeontologists as well as well-known Canadian palaeontologist Philip Currie from the University of Alberta [1]. It comes from the Luanchuan County of Henan Province. Unfortunately, the exact age of the the formation is unknown, but it is likely from the Late Cretaceous based on the other animals that are found in this formation. The name Yulong is derived from the Chinese "Yu", the abbreviated name for Henan Province, and "long" meaning dragon. Only one species of Yulong is currently known, Yulong mini in reference to the fact that the specimens are very small. 

Photograph of 3 Yulong mini skulls (a-c) in right lateral view and d in right lateral view (from Lu et al. [1]). Note the scale bar showing how small these skulls are! 

Yulong was an oviraptorid dinosaur of approximately chicken size. Most oviraptorids are larger, and can reach sizes up to 8 m in length. Although Yulong is described as being chicken sized, it was likely larger as the fossils that have been found are all juveniles. Several specimens are known, including well preserved skeletons, skulls, and even a well preserved embryo coming from a nest of 26 eggs. A thin section through a rib showed no growth lines, suggesting the animal was not yet a year old when it died. 

That's it for Yulong as it's a fairly newly described species. Tune in next week for our final dinosaur of the alphabet to learn about a neat theropod from Argentina!

References:
1. Lu, J. et al. 2013. Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications. Naturwissenschaften 100: 165-175.  

X is for Xenoceratops

Today we introduce the final Albertan dinosaur from our Albertan dinosaurian alphabet with 'X is for Xenoceratops'. This dinosaur is the only one from Alberta that starts with 'X', and was named only last year. 

In 1958, a well-known American palaeontologist named Wann Langston Jr. discovered a partial skull of a ceratopsian in the Foremost Formation (near the town of Foremost) of southern Alberta. These remains were then returned to the Canadian Museum of Nature in Ottawa, and were left undescribed. 50 years later, some palaeontologists became aware of these bones, and wondered about the animal that they belong to. Upon further examination, they concluded that it was a new animal, and named it Xenoceratops foremostensis [1]. The name Xenoceratops means 'foreign/alien horned face', referring to the fact that it is the only known ceratopsian from the Foremost Formation. It lived during the Late Cretaceous, about 78 million years ago, making it the oldest known ceratopsian found in Canada so far. 

Reconstruction of the frill of Xenoceratops foremostensis (centre) from Ryan et al. [1]

Xenoceratops was a centrosaurine ceratopsian, a group of dinosaurs that get their name from another Albertan ceratopsian, Centrosaurus. In the above image, Xenoceratops is surrounded by other centrosaurines including Centrosaurus (B), Styracosaurus (C) and Pachyrhinosaurus (F). As you can see, it has a very different frill from the others: the midline of the frill bore two thick bony knobs,  two pointed spikes (pointing to the rear and top of the animal in life), several small bumps, and a larger bony projection in the most anterior (forward) position. 

Through analysis of the bones, they determined that Xenoceratops was the most primitive centrosaurine found thus far. Unfortunately, the fragmentary nature of the remains makes it difficult to know for sure where it would have sat in the ceratopsian family. An unprepared skull found in the same region in 2010 does have portions of the face including elongated orbital horns, and has been referred to Xenoceratops. It also may have had  low, ridge-like nasal ornamentation, like those seen in Albertaceratops and Medusaceratops. 

This find was especially exciting for palaeontologists as it was only the second dinosaur fossil found in the Foremost Formation from more than just teeth. Very few outcrops of this formation are present, making it difficult to excavate and less likely to find fossils than the younger Oldman and Dinosaur Park Formations also of southern Alberta. Unsurprisingly, the species found in this formation are from known groups of dinosaurs from this area, but they are consistently more basal in their respective groups. 

Xenoceratops is yet another ceratopsian from Alberta, and is unfortunately the last dinosaur that we will talk about from Alberta, since no 'Y' or 'Z' dinos exist from our province. Stay tuned for next week, with a theropod from China!

References
1. Ryan, M.J., et al. 2012. A new ceratopsid from the Foremost Formation (middle Campanian) of Alberta. Canadian Journal of Earth Sciences 49: 1251-1262.

W is for Wintonotitan

Unfortunately, there are no dinosaurs that start with 'W' from Alberta, so we're going to talk about a dinosaur from Australia this week. You may have noticed that I haven't talked about any sauropods (long-necked dinosaurs) at all during this series. That is because no sauropod fossils have ever been found in Alberta, so I'm going to take advantage of that and talk about a sauropod from Australia in 'W is for Wintonotitan'.

Wintonotitan fossils were first found in 1974, but were named to the genus Austrosaurus, the only Cretaceous sauropod from Australia known at that time. In 2009, the partial skeleton originally found consisting of a scapula (shoulder blade), partial left and right arms, and fragmentary vertebrae, ribs, hips and more were named as the type specimen of Wintonotitan wattsi [1]. Some caudal (tail) vertebrae found later were also referred to this species. It lived during the mid Cretaceous (approximately 100 million years ago) of Australia, found near a town in the northwest (Queensland) called Winton, hence the name. It is a basal titanosauriform, which includes well known dinosaurs like Saltasaurus and Argentinosaurus, and like other sauropods, it was a large herbivore that walked on all four legs. The fossils of Wintonotitan were found in a sandstone, along with fish fragments, a theropod tooth, and several plant fossils. It lived alongside pterosaurs, other dinosaurs like Australovenator and Diamantinasaurus, insects, bivalves, and more. It lived among many plants like ferns, ginkgoes, flowering plants, and more.

Wintonotitan by T. Tishler from Hocknull et al. [1]

And that's it for Wintonotitan! Next week, we'll talk about our final Albertan dinosaur in the alphabet, with 'X'. Also, don't forget, we are now open to the public for the season! Why not plan to visit us this weekend? The forecast looks great!

References
1. Hocknull, S.A. et al. 2009. New mid-Cretaceous (latest Albian) dinosaurs from Winton, Queensland, Australia. PLoS ONE 4: e6190. doi:10.1371/journal.pone.0006190