Paleo Profiles: Spinosaurus

From the National Geographic Museum

A recent discovery, as of writing, has once again changed how we view the large, carnivorous dinosaur Spinosaurus. Every new discovery revolutionises how we see this dinosaur, and truly shows how diverse dinosaurs were as a group. While fairly accurate for its time of release, Jurassic Park III boasted that they were showing a carnivore larger than Tyrannosaurus, but since then new discoveries have completely changed how we see Spinosaurus. A new discovery could mean this blog could become quickly outdated. I also want to stress, the recent paper is still somewhat contested so bare that in mind while reading today.

Discovery and Fossils

Saying that Spinosaurus changed with each discovery is an understatement. The first fossils of Spinosaurus were discovered in the Bahariya Formation in Egypt in 1912, and was later formally described by German palaeontologist Ernst Stromer. He could tell from the fragmentary remains that it was a theropod, the bipedal carnivorous dinosaurs, but it had curious neural spines which formed a sail on its back. Due to this, Stromer named it Spinosaurus aegyptiacus, 'Spined Lizard from Egypt', and with the fragmentary remains he based the reconstruction on another, recently discovered, big theropod - Tyrannosaurus. Spinosaurus was reconstructed as being like a T rex with a sail on its back, but scientific knowledge of the 1910s meant that it was portrayed as dragging its tail along the ground. Stromer would discover many other dinosaurs from Egypt, but they are all sadly lost. An Allied bombing raid in 1944 destroyed the museum which kept Stromer's fossils, and the specimens were destroyed. As a result, a new reconstruction wasn't made until the 1990s! With the destruction of Stromer's specimens palaeontologists found it hard to identify which fossils belonged to Spinosaurus, however, new discoveries and other spinosaurids being found, such as the Baryonyx from England, allowed a new reconstruction. This one changed the skull from resembling a tyrannosaur, to the one we have today with an elongated jaw - this is the reconstruction used in Jurassic Park III. In 1996 a new find from Morocco indicated a possible second species, but that it still heavily debated with palaeontologists debating whether it is the same species as the first one discovered. Then, in the mid-2000s, it was discovered to have a small crest on its head, and in the late-2000s a well-preserved snout revealed a series of nerves. Isotope analysis, mixed with this, indicated that Spinosaurus was largely a fish eater - something long theorised which was now confirmed.

From 1915 to 2014 to 2020, from National Geographic

A 2014 paper, led by Nizar Ibrahim revolutionised how Spinosaurus has been reconstructed. This paper made the dinosaur a quadruped, semi-aquatic, and had a newly shaped sail, which was likely covered in some skin. This caused waves in the palaeontological community, albeit for some controversial reasons. Many agreed that Ibrahim's reconstruction, which utilised 3D modelling, offered a new insight into the life of Spinosaurus - palaeontologists had realised that it was top-heavy, but a quadrupedal lifestyle would solve that issue. However, as Ibrahim had combined several specimens together it was criticised, and the reconstruction shortened the hind legs of the Spinosaurus. It was seen as being a combination, and not an actual specimen, and the now shorter hind legs created issues with other spinosaurids. Baryonyx and Suchomimus, for example, had much longer hind legs, although the only specimens of these animals were juveniles. Others have theorised that younger spinosaurids had longer legs which ceased to grow at the same rate as the rest of the body as the animal aged. This brings us to 2020. Ibrahim and his team had discovered more tail bones of a Spinosaurus, something which had not been found before. Neural spines and chevrons were found on the tail, these spines were long, and did not overlap allowing flexibility. This means that the tail was adapted to an aquatic lifestyle - it has a resemblance to a crocodile's tail. Spinosaurus had gone from a sailed bipedal lizard which dragged its tail on the ground, to a fish-eating, aquatic or semi-aquatic dinosaur.

Biology

The spines at the National Geographic Museum

We've largely looked at the biology of the Spinosaurus in the discussion about the fossils discovered, so we'll go over it quickly here. The most iconic aspect of Spinosaurus is its 'sail'. Since the early-2000s it has been debated whether it was a sail or a hump - something which would heavily determine what type of lifestyle the Spinosaurus had. One theory, which is widely accepted regardless of whether it was a hump or sail, is that it could be used for display - bright and intimidating colours, including the sheer size of it, could be used to deter rivals or attract mates. When it was more accepted that dinosaurs were cold-blooded, a theory argued that the sail could be used for thermoregulation with the Spinosaurus basking in the sun to warm itself up. However, it has largely been found that dinosaurs, especially larger dinosaurs, were more warm-blooded than cold, with them likely being somewhere in-between. Consequently, this theory has largely gone out of favour. The hump theory argues that it is a fatty buildup to sustain the dinosaur while it was searching for new food reserves. Since 2014, it has generally been seen as some form of 'sail' with skin covering it. With recent discoveries revealing an increasingly aquatic lifestyle, a likely function was to aid in locomotion. Ibrahim's findings have revealed a much more streamlined animal making it more aerodynamic to cut through the water. The 'sail' would serve as a way to cut through the water more efficiently.

The new tail, from National Geographic

The new paper is still being debated - Mark Witton, for example, has argued that the tail bones may not be entirely suited to an aquatic lifestyle. However, we do see a lifestyle mostly suited for the water, maybe a semi-aquatic one like a crocodile. Ibrahim has reconstructed the dinosaur with webbed feet, for example. Before 2014 it was assumed to be a terrestrial animal which fed on fish - the long snout with crocodile-like teeth was suited to grabbing hold of fish, it had strong forearms to swipe at its prey, and its skull seemed adapted to standing for long-hours at the waterside. The BBC documentary Planet Dinosaur, for example, used this idea. This theory had Spinosaurus hunting like a heron or stork, largely based on the skull. The eyes and nostrils are high up the head while the snout was covered in nerves and receptors. The snout could be in the water to detect movement, while the nostrils and eyes could be out of the water, so it could see what it was hunting and it could still breathe. However, the recent discoveries has changed how this would work. Instead, Spinosaurus would hunt like a crocodilian - using its sensitive snout to find fish and turtles through the murky waters. With the nostrils and eyes high up the head, this would allow the Spinosaurus to poke its head out of the water while remaining submerged. The new shorter hind legs is part of the aquatic lifestyle - short but muscular to give propulsion to power the dinosaur through the water.

Finally, we have the size of the Spinosaurus itself. Until relatively recently many of the established sizes were estimates. Even today, the size of the Spinosaurus is still based on estimates. Back when Spinosaurus was thought to be bipedal estimates placed the dinosaur at over 4 metres in height (discounting its sail), but the recent findings have placed this as being around 3 metres (again discounting the sail). The original height placed it as being one of the most, if not the most, tallest carnivorous dinosaurs - taller than the Tyrannosaurus. Spinosaurus is still very big coming to a minimum length of 15 metres (about 49 foot), and its largest length is estimated to be around 18 metres (59 foot). Its skull was big coming to around 1.75 metres (5.7 foot) from snout to the back of the skull. It was full of teeth evolved to grasp hold of fish, these teeth could be over an inch in length.

When and Where 

Unfortunately for Jurassic Park III fans, Spinosaurus would never have met Tyrannosaurus. Not only is it found in an entirely different continent, but it lived several million years before the Tyrannosaurus came about. Tyrannosaurus evolved at the very end of the Cretaceous period being one of the last dinosaurs, whereas Spinosaurus lived in the early Cretaceous until the late Cretaceous. The oldest fossils date around 112 million years ago, and the most recent fossils have been dated to around 93 million years ago. This was a time when large, carnivorous dinosaurs became very diverse. There were the spinosaurids, abelisaurids, tyrannosaurids, carcharodontasaurids to name a few. Spinosaurus, meanwhile, lived in two areas - the Bahariya Formation in Egypt and the Kem Kem Beds in Morocco. As a result, both species are named in reference to where they have been found: Spinosaurus aegyptiacus and Spinosaurus maroccanus. However, as mentioned earlier, there have been debates about whether the Moroccan species is actually the Egyptian species. 

The World of Spinosaurus

From National Geographic, Art by Davide Bonadonna

Knowing that Spinosaurus was aquatic, or semi-aquatic, you may be wondering why the Spinosaurus lived in the arid regions of North Africa. However, back in the Cretaceous North Africa was a shoreline and a mangrove forest creating the perfect environment for a giant, crocodile-like dinosaur. Both sites where the dinosaur has been found are full of a diverse range of fish and aquatic life - sharks, sawfish, coelacanths, lung fish, ammonites, crabs, oysters, rays, and crocodiles. A mangrove swamp full of life with access to the sea proved to be the perfect habitat for the Spinosaurus. Other dinosaurs lived in the region including the giant sauropods (long-necked dinosaurs) Paralititan and Aegyptosaurus. However, the Bahariya Formation and Kem Kem Beds were full of giant carnivorous dinosaurs - these places have been described as possibly the most dangerous places to go on safari in history. Possibly the largest carnivorous dinosaur Carcharodontosaurus were found here, as well as many other big carnivores like Deltadromeus and Rugops being just the most well known. With so many carnivores around it is evident that they had to specialise to avoid competition, Spinosaurus could happily hunt the waves to avoid contact with a hungry Carcharodontosaurus. This does not mean there were overlaps in prey. The spinosaurid Baryonyx has been found to have preyed upon the herbivorous Iguanodon, so it is not too far-fetched that the Spinosaurus could prey on dinosaurs which went too close to the shoreline. Neural spines have been found with chunks taken out of them by a large carnivore, likely Carcharodontosaurus, indicating that at times clashes could have happened. 

The sources I have used are as follows:

-Michael Greshko, 'Bizarre Spinosaurus makes history as first known swimming dinosaur', National Geographic, (29/04/2020), [Accesed 08/05/2020]

-Jason Treat and Mesa Schumacher, 'Reconstructing a Gigantic Aquatic Predator', National Geographic, (29/04/2020), [Accessed 08/05/2020]

-'Spinosaurus', Prehistoric-Wildlife.com, [Accessed 08/05/2020]

-Ben G Thomas, 'The New Look of Spinosaurus', YouTube, (03/05/2020), [Accessed 08/05/2020]

-Trey the Explainer, '"New" Spinosaurus', YouTube, (30/05/2015), [Accessed 08/05/2020]

-Nizar Ibrahim, Simone Maganuco, Cristiano Dal Sasso, Matteo Fabbri, Marco Auditore, Gabriele Bindellini, David M. Martill, Samir Zouhri, Diego A. Mattarelli, David M. Unwin, Jasmina Wiemann, Davide Bonadonna, Ayoub Amane, Juliana Jakubczak, Ulrich Joger, George V. Lauder & Stephanie E. Pierce, 'Tail-propelled aquatic locomotion in a theropod dinosaur', Nature, 581, (2020), 67-70

-Nizar Ibrahim1, Paul C. Sereno, Cristiano Dal Sasso, Simone Maganuco, Matteo Fabbri, David M. Martill, Samir Zouhri, Nathan Myhrvold, and Dawid A. Iurino, 'Semiaquatic adaptations in a giant predatory dinosaur', Science, 345:6204, (2014), 1613-1616

-Thomas Holtz, 'Spinosaurs as crocodile mimics', Science, 282:5392, (1998), 1276-1277

-Simone Maganuco and Cristiano Dal Sasso, 'The smallest biggest theropod dinosaur: a tiny pedal ungual of a juvenile Spinosaurus from the Cretaceous of Morocco', PeerJ, (2018), 6

-Jan Gimsa, Robert Sleigh, and Ulrike Gimsa, 'The riddle of Spinosaurus aegyptiacus’ dorsal sail', Geological Magazine, 153:3, (2016), 544-547

-Planet Dinosaur, (2011), BBC, 14 September

Thank you for reading. For other Paleo Profiles we have a list here, and for other blog posts we have a Facebook or catch me on Twitter @LewisTwiby.

Paleo Profiles: Nasutoceratops

A reconstructed skull in the Arizona History of Natural History

Recently, the video game Jurassic World: Evolution announced that it would be introducing the not very well known herbivorous dinosaur Nasutoceratops. The Nasutoceratops was a car-sized dinosaur, and is often shadowed, alongside many of its other relatives, by one particular dinosaur which it's related to: Triceratops. Today we'll look at the Nasutoceratops, how it lived, and how it might have behaved.

Discovery and Fossils

Parts of the holotype

Nasutoceratops is a very recent discovery being first found in 2006, and its official description only took until 2013 - quite often fossils can be studied for over a decade before being officially described. A team from the University of Utah found most of a skull and several leg bones in the Kaiparowits Formation, Utah. The amount of well-preserved bones from a specimen, especially the skull, allowed palaeontologists to feel confident enough to name the dinosaur very quickly. As early as 2010 one of the discoverers, Eric Lund, named the dinosaur, but it took until 2013 for the official description to happen. It was named Nasutoceratops titusi meaning 'Large Nosed Horned Face'. A relative of the Triceratops ('Three Horned Face') they thought it was fitting to give it a similar name, especially as the Nasutoceratops had a very distinct nose just like Triceratops.

Biology

The Nasutoceratops belonged to a family of dinosaurs called the Ceratopsidae, or Ceratopsids. These were a family of quadrupedal herbivorous dinosaurs characterised by beaked jaws and elaborate nasal horns. The ceratopsids a further split between two subfamilies - the chasmosaurids and centrosaurids. The chasmosaurids, including Triceratops, were characterised by their large brow horns and elaborate triangular frills; whereas the centrosaurids, which Nasutoceratops belonged to, had elaborate nasal horns, short rectangular frills, but had elaborate spines on the frills. Although Nasutoceratops is classed as a centrosaurid it shares several features of chasmosaurids, such as lacking elaborate spines on the frill and having long brow horns, but the group who described the dinosaur stated that possible convergent evolution was due to this. This is when two or more species, or groups, evolve independently but similarly to suit similar environments - such as how bats and birds are not related but both evolved powered flight for a specific environment. The skull of a Nasutoceratops is a blend of centrosaurid and chasmosaurid skulls as a result. If you looked at a Nasutoceratops head on you would notice how the horns resemble that of cattle and not like Triceratops. Instead of being relatively straight, like that of Triceratops, they curve horizontally so they resemble cattle horns. These horns were very long, the longest among centrosaurids, covering 40% of the 1.5 metre (4.9 ft) long skull - they stretches from the brow to just before the snout. The snout itself is very interesting. Centrosaurids are renowned for their unusual snouts, and Nasutoceratops keeps this precedent by exhibiting a large bony nasal snout, shown below.

A Nasutoceratops skull, from Sampson, Lund, Loewen, Farke and Clayton

Based on the skull size and the preserved front leg bones palaeontologists have estimated that Nasutoceratops was just under 5 metres long. Based on bone texture, the specimen which we have was likely a sub-adult or adult, so it was close to either its full size or close to it. What would a living Nasutoceratops look like? Unfortunately, no skin has been preserved from Nasutoceratops, but based on other species we can make some realistic assumptions. Scott Sampson has suggested that sexual dimorphism may have occurred in ceratopsians. Only a few early ceratopsians, like Protoceratops, show skeletal differences, so Sampson suggested that if there was dimorphism it would be based on the frills. Males would likely have brightly coloured frills to attract mates or scare of rivals - only in a last resort would they use their horns to fight like modern bighorn sheep. Horns could snap, fights could leave deep wounds, and with predators about it was often too risky. There have been debates about whether they would live in herds - traditionally reconstructions have presented ceratopsids as living in herds like modern African buffalo or white rhino. Sampson has suggested that they lived in 'socially complex' herds, while others have suggested that, when herds have been found, that they could be seasonal or herds of young dinosaurs. Modern Indian rhinos form 'bachelor' herds for protection, as an example. Unfortunately, this does not have a simple answer. Finally, Nasutoceratops likely had some feathers. As we have regularly discussed, every year palaeontologists uncover new revolutionary discoveries opening greater insight into the life of the dinosaurs. The discovery of feathers, ranging from hair-like filaments to modern feathers, on dinosaurs is one example. Although no feathers have been found on large ceratopsians, but a primitive ancestor to the ceratopsians have been found with quill-like follicles. A Psittacosaurus found in the Yixian Formation, China was found with these bristles. What they were used for has been debated: display? defence? thermoregulation? It is likely that larger species, like Nasutoceratops, likely had these bristles, which can be seen on a reconstruction of Psittacosaurus below:

Diet

Ceratopsids had leaf-shaped teeth in a beaked mouth, and Nasutoceratops had this design as well. This was perfect for slicing apart tough vegetation close to the ground. Nasutoceratops lived alongside many other species of herbivorous dinosaurs, so an adaptation to low-lying plants would help prevent interspecies competition. The thick beak could slice through tough vegetation which their leaf-shaped teeth could easily slice into smaller pieces. Due to the high fibrous foliage which they ate Nasutoceratops likely had some form of fermentation in its stomach to further break down the vegetation, as modern elephants and rhinos do, to increase nutrient extraction from what they eat. It has been suggested recently that ceratopsids could have scavenged from the kills of carnivores or would eat abandoned eggs in nests for extra protein. This is not unheard of in nature. Deer have regularly been caught eating dead squirrels or scavenging from carcasses, and hippos have even been reported eating other dead hippos! Herbivores have to eat a lot to have enough energy, so scavenging meat would be a quick way to regain lost protein. Meat and eggs would supplement their diet when needed.

When and Where

The Western Interior Seaway

As mentioned earlier Nasutoceratops was discovered in the Kaiparowits Formation in what is now Utah. This is quite unusual for centrosaurids, as most American centrosaurids are found in the North-East US and Canada, meanwhile Nasutoceratops is one of two to be known from outside this region - the other being Diabloceratops. The 'when' answers why this is. Ceratopsians are known from the Late Cretaceous, around 83 to 66 million years ago, and Nasutoceratops lived in a specific time called the Campanian, around 75 million years ago. At this time the United States was split in two by a great inland sea called the Western Interior Seaway. This isolated small pockets of dinosaurs where certain groups were located in only certain locations. Nasutoceratops was descended from a small population of earlier ceratopsians separated from larger populations by the seaway. It also created a warm, wet and humid jungle which Nasutoceratops could be found in. Floodplains and swamps provided ample plant diversity to sustain a wide range of prehistoric life. The Kaiparowits Formation is one of the best fossil sites in the US and has revealed a thriving Cretaceous ecosystem. Two other ceratopsids lived alongside Nasutoceratops, including the elaborately-frilled chasmosaurid Kosmoceratops, and the duckbilled hadrosaurs, including the famous Parasaurolophus. There were threats to Nasutoceratops; the young could fall victim to the raptor Talos and a fully grown adult could potentially be taken down by a tyrannosaurid called Teratophoneous. Although, in the water there was a crocodilian that could eat dinosaurs called Deinosuchus.

The sources I have used are as follows:

-Gregory S. Paul, The Princeton Field Guide to Dinosaurs, Second Edition, (Princeton: Princeton University Press, 2016)

-Eric Lund, Scott Sampson, and Mark Loewen, 'Nasutoceratops titusi (Ornithischia, Ceratopsidae), a basal centrosaurine ceratopsid from the Kaiparowits Formation, southern Utah', Journal of Vertebrate History, 36:2, (2016)

-'Nasutoceratops', Prehistoric-Wildlife.com, [Accessed 31/08/2019]

-Scott Sampson, Eric Lund, Mark Loewen, Andrew Farke, and Katherine Clayton, 'A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia', Proceedings: Biological Sciences, 280:1766, (2013), 1-7

-Peter Dodson, The Horned Dinosaurs: A Natural History, (Princeton: Princeton University Press, 1996/2017) 

Thank you for reading and I hope you found it interesting. For other Paleo Profiles we have a list here. For future blog updates please see our Facebook or catch me on Twitter @LewisTwiby.

Paleo Profiles: Dilophosaurus

The reconstructed holotype at the Royal Ontario Museum

One of the most iconic dinosaurs from Jurassic Park is the crested Dilophosaurus which blinded and ate the hapless Dennis Nedry in one of the most iconic scenes of the movie. The Jurassic Park version of the Dilophosaurus has gone on to inspire recreations of the dinosaur in popular media, ranging from toys to video games. However, the real Dilophosaurus was fairly different from its Hollywood counterpart.

Discovery and Fossils

The Dilophosaurus was first discovered in 1942 by American palaeontologist Charles Camp, who was on an expedition to find vertebrate fossils in northern Arizona. In the Kayenta Formation, guided by local Navajo, the expedition found three dinosaur skeletons. While two were very eroded, the first one they found was almost complete. As always with fossils, there was a large gap in time between initial discovery and description, and the dinosaur was not named until 1954 by palaeontologist Samuel P. Welles. However, he believed that the new dinosaur was a species of an already discovered dinosaur called Megalosaurus, which was actually the first discovered/named dinosaur. Welles named the fossil Megalosaurus wetherelli after a Navajo councillor whose nephew had help discover the fossil, and who had helped the expedition himself. Megalosaurus has been seen as a 'wastebasket taxon' - a taxon where organisms don't seem to fit anywhere else are put in there. In 1964 Welles returned to the Kayenta Formation to find more fossils, and he found another near complete skeleton where the three earlier ones had found. What he found made him realise that Megalosaurus wetherelli was not as they initially thought. The skull of the new discovery had crests, and the dinosaur was overall larger than the earlier finds. Upon re-examining the holotype Welles realised that the crests had become dislodged from the skull, so he had the dinosaur renamed to Dilophosaurus wetherelli - 'Two-crested Lizard'. New fossils were found and in 1987 a near complete skeleton was discovered in Lufeng Province, China, and a few years later named Dilophosaurus sinensis. It was later discovered to not be actually a Dilophosaurus, but instead another species of a different dinosaur called Sinosaurus in 2017.

Biology

The real life Dilophosaurus differed greatly from its appearance in Jurassic Park

Dilophosaurus was a theropod dinosaur - this was a suborder of dinosaurs characterised by bipedal stances. This order includes many different species ranging from modern birds to the Tyrannosaurus. Existing at the very start of the Jurassic Period Dilophosaurus this means that it was one of the earliest theropods, and definitely one of the earliest large carnivores. When it was alive it would have been one of the largest carnivorous dinosaurs on the planet; from snout to tail it could reach 6 metres long, and could reach heights of up to 2 metres. Very different from the diminutive version in the movies. The initial three skeletons found were determined to be juveniles as the fossil found by Welles was much larger than the first three. An adult would therefore be the size of a brown bear. Just like a bear Dilophosaurus had very powerful arms - this will become important later. They were likely quite hardy animals. Phil Senter and Sara Juengst in 2016 found that one specimen had eight fairly bad injuries. However, most of the injuries showed signs of healing indicating that it could have lived years after getting initially wounded. A reason why it might have survived so long is possible evidence of pack behaviour. As specimens of similar ages have been found together it has led to the suggestion that they worked and lived together to survive - it would explain how the injured one lived. However, we cannot be entirely certain - a flash flood could explain why they were found together, especially considering how well preserved some specimens are. We now know that most dinosaurs would be feathered by the end of the Jurassic, but palaeontologists have been debating about when feathers developed. We have yet to find evidence of feathers on Dilophosaurus itself, but in 2004 Martin Kundrat reported finding traces of filaments from downy feathers on a theropod dinosaur from early Jurassic Massachusetts. If this dinosaur had some form of feathers it is not out of the question that Dilophosaurus also did so. Senter and Juengst even found that their specimen had a deformed humerus and finger thanks to developmental osteodysplasia - a condition previously only found in modern birds. If a Dilophosaurus has been found with this condition, this indicates that it more than likely had feathering.

A skull in the Royal Tyrell Museum

The most iconic part of Dilophosaurus is easily its crest. Unlike in Jurassic Park, the Dilophosaurus never had a frill - that was made up for the film, likely so audiences would not get it confused with the Velociraptors. The v-shaped crest shaped have often been disarticulated from the skull so for a while palaeontologists were not sure how it would go on the animal's head. Quite possibly the initial three specimens had their crests preserved, but as the expedition team did not know they existed consequently did not look for them. Initial reconstructions had the crest resting on the back of the skull and going onto the neck; this has since been rejected as it would restrict the neck's movement. Instead the crest started at the front of the skull and ended at the back. A real life equivalent could be the crest of a male cassowary, as shown below:

What were the crests used for? Initial theories of combat or thermoregulation have been rejected, so visual display is a likely function. Theropod dinosaurs likely could see bright colours as modern birds do, so the crests would be brightly coloured. Male Dilophosaurus would have the brightest crests in order to attract a mate, or scare off rival males. Finally, we have the jaw, which features a large notch in the upper jaw. This made it very weak - Dilophosaurus would be unable to break through bone. This led to questions about how or what it could eat - when writing Jurassic Park Michael Crichton theorised that they were venomous. We have no evidence for this, but palaeontologists have theorised how and what it ate.

Diet 

One of the biggest questions concerning the Dilophosaurus is its diet. With a weak jaw hunting down prey like a modern lion or wolf could be potentially dangerous. One wrong bite and its jaw would be broken. Different theories about how Dilophosaurus could have eaten. For one, it had very strong arms. Long, powerful arms, like a bear, could be used instead of its jaws to attack prey, and potential pack behaviour could improve the chances of a successful kill. One swipe could do serious damage, and an injured animal would be unable to escape when surrounded by other dinosaurs. Hence, its jaw would only need to be strong enough to tear flesh from a carcass, and even then the strong arms could also be used to break a carcass into smaller, manageable pieces. Some palaeontologists did suggest that Dilophosaurus was a scavenger, but as no living large animal exists entirely by scavenging this hypothesis has been rejected. A later theory suggested that the jaws weren't used for killing prey, but rather holding prey. Dilophosaurus lived alongside many smaller animals ranging from herbivorous dinosaurs to frogs, so they would be its primary food source. A Dilophosaurus would catch a small animal where its front teeth would slash the prey, by the time it reached the back of the jaws the prey would be too weak to resist. Andrew Milner and James Kirkland in 2000 suggested a new theory which has become increasingly accepted. The Kayenta Formation has been discovered to be rather wet, and many fish fossils have been found there. Most importantly, wading marks have been found from carnivorous dinosaurs indicating the diet of Dilophosaurus: fish. The strong arms show signs of being even able to grip prey so a diet of fish would be ideal. Like a bear, Dilophosaurus would wade into water where it would swipe up fish to eat in its weak jaws. Milner and Kirkland have found that Dilophosaurus had similar adaptations to the known fish-eating Spinosaurus: long teeth near the front of the skull to hold fish in place; long and strong arms; and nostrils further back in the skull to avoid water entering them. It is therefore likely that Dilophosaurus waded into water to catch fish and other aquatic life.

When and Where

The reconstructed model 'Dyzio' in the Geological Museum of the State Geological Institute in Warsaw

Dilophosaurus lived 193 million years ago in the Early Jurassic. Dinosaurs had begun to fully evolve as a distinct group during the Mid to Late Triassic, and the Late Triassic extinction left them as the dominant terrestrial group. At this time most of the best known dinosaur orders - like stegosaurids, sauropods, and tyrannosaurids - had yet to evolve. Dilophosaurus would have been one of the largest carnivores, especially as large terrestrial life had yet to bounce back from the Triassic-Jurassic extinction. This is also a reason why Dilophosaurus likely had a diet consisting of fish: there were few large herbivorous dinosaurs to hunt. We have currently only found Dilophosaurus in Arizona, but the formation group which the Kayenta Formation is part of comprise most of the South-west United States. We probably could have seen Dilophosaurus in this region as well. Unlike contemporary Arizona, the Kayenta Formation was humid and wet with plenty of lakes and rivers. Rivers preserve fossils well as the sediment protects specimens from the elements. The high number of well preserved specimens, including the first Dilophosaurus to be found, and high number of aquatic animals in the area show this. Dilophosaurus lived in an environment closer to modern Florida than modern Arizona.

Thank you for reading. The sources I have used are as follows:

-Gregory S. Paul, The Princeton Field Guide to Dinosaurs, Second Edition, (Princeton: Princeton University Press, 2016)

-S.P. Welles, 'New Jurassic Dinosaur from the Kayenta Formation of Arizona', GSA Bulletin, 65:6, (1954), 591-598

-S.P. Welles, 'Dilophosaurus (Reptilia: Saurischia), A New Name for a Dinosaur', Journal of Paleontology, 44:5, (1970), 989

-S.P. Welles, 'Dilophosaurus wetherilli dinosauria theropoda osteology and comparisons', Palaeontographica Abteilung A Palaeozoologie-Stratigraphie,185:4-6, (1984), 85-180

-Robert Gay, 'New specimens of Dilophosaurus wetherilli (Dinosauria: Theropoda) from the early Jurassic Kayenta Formation of northern Arizona', Western Association of Vertebrate Paleontologists Annual Meeting Volume Mesa, Arizona, 1:1, (2001)

-'Dilophosaurus', Prehistoric-Wildlife.com, [Accessed 12/07/2019]

-Phil Senter and Sara Juengst, 'Record-Breaking Pain: The Largest Number and Variety of Forelimb Bone Maladies in a Theropod Dinosaur', PLoS ONE, 11:2, (2016), 1-13

-Martin Kundrat, 'When did Theropods Become Feathered? - Evidence for Pre-Archaeopteryx Feathery Appendages', Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 320B:4, (2004), 355-364

-Andrew Milner and James Kirkland, 'The Case for Fishing Dinosaurs at St. George Dinosaur Discovery Site at Johnstone Farm', Survey Notes of the Utah Geological Survey, (2007), 39, 1-3

Thank you for reading and I hope you found it interesting. For other Paleo Profiles we have a list here, and for future blog updates please see our Facebook page or catch me on Twitter @LewisTwiby.

Paleo Profiles: Yi qi

A reconstruction of the Yi qi. From Emily Willoughby, emilywilloughby.com, (May 2015)

Today on Paleo Profiles we will be looking at a very unique dinosaur from Jurassic China: the Yi qi (Strange Wing). This bat like dinosaur is a recent discovery and shows us how diverse dinosaurs were. So let's look at China's bat-like 'Strange Wing'.

Discovery and Fossils

Currently, we only have own partial specimen of Yi and it was only formally described in 2015. It was initially discovered by a farmer called Wang Jianrong in Qinglong County back in 2007; he recognised it as a possible dinosaur fossil so he sold it to the Shandong Tianyu Museum of Nature. As often with fossil discoveries, it remained in storage until someone could formally describe the fossil in 2015. A group of ten palaeontologists evaluated the fossil including Xu Xing - Xu is one of China's most prominent palaeontologists describing, or co-describing, many major discoveries including the bird-like Microraptor and the fossil which showed tyrannosaurs were feathered, Yutyrannus. In 2015 their findings were published in Nature and the little dinosaur was named Yi. Although partial, major sections of the Yi has been preserved including the majority of the pigeon-sized body, parts of the skull, and imprints from a membrane which made up the animal's wings.

Biology

Examples of the Yi qi soft tissue

Yi was in a family known as Scansoriopterygids - a family which was closely related to the ancestors to modern birds. Three genera, including Yi, made up the Scansoriopterygids which are all biologically similar and lived alongside one another. The largest, and best known before 2015, was the Epidexipteryx due to it being the best preserved. However, for years it had been reconstructed incorrectly. Yi was the first Scansoriopterygid to be discovered with preserved membranes which connected the long fingers together, and palaeontologists, and paleo-artists, at times have a general fault of 'skin-wrapping' fossils. This means that non-mammalian fossils are regularly reconstructed with the skin tracing the skeletons - features like muscles, filaments, or extra skin are often overlooked. As a result Epidexipteryx was reconstructed without membranes leading to palaeontologists believing that it lived similar to a species of lemur called the aye-aye. The BBC documentary Planet Dinosaur reconstructed Epidexipteryx in this way as well:

The discovery of the Yi showed that Scansoriopterygids were not like aye-ayes, but really bats or more likely flying squirrels. This had been suggested before the discovery of Yi - most notably by Andrea Cau. Although we have the membrane of the Yi it is not fully preserved so there are several different reconstructions of the wing - the discoverers stated that 'the flight apparatus of Yi cannot be confidently reconstructed...However, the range of possible flight apparatus configurations can be explored by considering different reconstructions'. When first discovered the media reported it as being a 'dinosaur bat' but the paper itself disagreed with that interpretation - Yi just vaguely resembled one. They argued that based on realistic membrane placement it would be a glider. Yi and other Scansoriopterygids had long tail feathers which have traditionally been seen as being for display. Likely that it still true, possibly brightly coloured it could be used to assert dominance or attract a mate, like with the feathers of a male peafowl. With the Scansoriopterygids they were also possibly used to help the dinosaurs glide - like the tail on a flying squirrel it could act as a rudder to steer. It did not have the exact body for relying solely on gliding so it could possibly rely on short bursts of powered flight.

One of the key discoveries associated with Yi and other Scansoriopterygids are the presence of feathers covering the body. They were closely related to the ancestors of modern birds, just instead being an evolutionary dead end, so it would be natural for them to be covered in feathers - albeit these were simple feathers, not something you would expect to see on a fully grown modern bird. Nevertheless, by use of an electron microscope it is possible to know, vaguely, what colour the feathers were. Preserved pigments leads us to believe that Yi had black feathers except on the head which was a yellow-brown hue. Yi and its cousins were perfectly adapted to life in the trees with flattened bodies and long fingers which allowed it to grip hold of tree trunks. The diet of Yi is still unknown but reasonable guesses can be made. Teeth and the presence of pterosaurs in the area with similar teeth would suggest that Scansoriopterygids were primarily insectivores, although their diet could include berries.

When and Where
Yi and other Scansoriopterygids lived during the Jurassic period, in particular the Callovian or Oxfordian, around 160 million years ago. During this time the world was warmer, wetter, and richer in oxygen. Where Yi came from was no exception. The Tiaojishan Formation in Northeast China has been believed to be either a sub-tropical or temperate climate, as well as being both warm and humid based on fossilised tree rings. As a result, the Yi would never experience the cold. Based on its arboreal lifestyle, and limited ability to undertake powered flight, this would mean that the Yi would be limited to forests. The region was very volcanic. Tiaojishan Formation has many layers showing occasional ash fall from volcanic eruptions - something that many Chinese fossil sights experienced. This is why Chinese dinosaurs are so well preserved that they regularly show evidence of feathers. Ash buries and preserves those unfortunate enough to be caught in the cloud - just think of how well-preserved the unfortunate victims of Pompeii are. Consequently, Chinese fossil sites every year gives us more and more well-preserved dinosaur remains - Yi is far from the only dinosaur that we know what colour they were due to their pigments being preserved.

Neighbours

A Jeholopterus, a pterosaur which lived alongside Yi

Yi had a wide variety of animal life living alongside it. Among these included the other two Scansoriopterygids genera, Scansoriopteryx and Epidexipteryx, but both were a lot smaller than the Yi. In fact, three of the smallest dinosaurs lived at the same time in the same place - Scansoriopteryx, Epidexipteryx, and Aurornis. Other arboreal dinosaurs resembled modern birds - such as Anchiornis - and likely competed with Yi. Pterosaurs were common in the region with around fifteen species being known to live alongside Yi. The Scansoriopterygids were not the only gliding animals - the flying squirrel like Volaticotherium could be found in the Tiaojishan forests. What about terrestrial dinosaurs? There are a few including a heterodontosaurid called Tianyulong and a few dinosaurs, including Anchiornis, lived alongside them. From other Chinese fossil sights around the same time we do know larger dinosaurs were roaming Jurassic China - such as Sinraptor, actually a relative of Allosaurus and not raptors. There is a possibility that a large carnivore related to Sinraptor stalked the land.

Thank you for reading. The sources I have used are as follows:
-Xing Xu, Xiaoting Zheng, Corwin Sullivan, Xiaoli Wang, Lida Xing, Yan Wang, Xiaomei Zhang, Jingmai K. O’Connor, Fucheng Zhang, & Yanhong Pan, 'A Bizarre Maniraptoran theropod with preserved evidence of membranous wings', Nature, 521:7550, (2015), 70-73
-'Yi', prehistoric-wildlife.com, [Accessed 20/03/2019]
-'Epidexipteryx', prehistoric-wildlife.com, [Accessed 20/03/2019]
-Gregory S. Paul, The Princeton Field Guide to Dinosaurs, Second Edition, (Princeton: Princeton University Press, 2016)
-Trey the Explainer, 'Paleo Profile - Yi qi', Youtube, (29/04/2015), [Accessed 20/03/2019]
-Wang Yongdong, Saiki Ken'ichi, Zhang Wu, and Zheng Shaeolin, 'Biodiversity and palaeoclimate of the Middle Jurassic floras from the Tiaojishan Formation in western Liaoning, China', Progress in Natural Science, 16:9, (2006), 222-230

Paleo Profiles: Introduction

For years palaeontology has been one of my great loves; so much so that I came very close in doing it as my degree at university. The creatures of the past have wowed peoples worldwide ranging from the monsters of the silver screen in Jurassic Park, Gojira, and The Valley of Gwangi to real life folklore and myths. With Paleo Profiles we look at different extinct animals ranging from dinosaurs to mammoths to giant bugs in order to understand what they were like when they roamed the Earth. This series will hopefully inform readers of the wonders of prehistory (and some more recently extinct forms of life). I also want to prefix this by saying that I am a historian, not a palaeontologist. This is something which is a hobby to me and not my field of study so I am not an authority on palaeontology. The purpose of Paleo Profiles is for me to engage in one of my great loves; for newcomers to palaeontology to find out some interesting information; and for those with an active interest/actual authority to also find out interesting points. For any Paleo Profiles if you feel that I've got something wrong or left something out please tell me and I will add it in. Palaeontology is a constantly evolving and changing field; just as much as archaeology and history. 

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Our first Paleo Profile will focus on a behemoth from the deep...