In Part Two, David talked about his favourite dinosaurs, whether we are still discovering new dinosaurs, and much more. If you missed it, click here to take a read.
Many of the images in the article ahead are also courtesy of our friends at Jurassic Vault – so go show them some love if you haven’t already!
Without any further ado, let’s kick off our final part to this series by talking about the accuracy of the fan favourite Spinosaurus!
How accurate was the Spinosaurus we saw in Jurassic Park 3 (2001) at the time of release?
The Spinosaurus of Jurassic Park III was actually reasonably accurate at the time of release, as it was not well known at the time. Its main problem was the orientation of the hands – as with most of the other theropods in the franchise, it was depicted with permanently pronated “bunny hands”, even though theropods were unable to pronate their hands into such a position.
How do you see/research intelligence of extinct animals that died millions of years ago?
We can get an idea of the cognition of an extinct animal by taking a cast of the interior surfaces of the braincase – producing what is known as an endocast. This used to be performed by injecting latex into a dinosaur braincase and then cutting it open. Fortunately, however, these days we are able to produce these digitally by CT-scanning dinosaur braincases. The endocast gives us a replica of the shape of the brain and surround soft tissues.
From this, we can examine the shape of the brain and its constituent lobes to get an idea of the sensory abilities of an animal, and from the dimensions of the inner ear we can even calculate the range of sounds an animal could hear. The overall size and shape of the brain also give us a rough idea of the animal’s intelligence relative to that of other creatures. We can then also compare this with other evidence of dinosaur behaviours, such as associations of skeletons and footprints, to get an idea of their cognition and behavioural complexity. However, it should be stated that brain size does not necessarily correlate tightly with intelligence, and certainly many animals with small brains are still capable of complex cognition and behaviours. Consequently, we can only get a vague impression of just how smart dinosaurs may have been.
Would a Mosasaurus have slept in the same way a Whale sleeps?
Sleeping poses a problem for marine animals that need to come up for air, but cannot haul out onto land. Whales have solved this by only putting part of the brain to sleep at a time, still allowing them to surface. Sea turtles, however, have different solutions. Sometimes they sleep floating at the surface. Otherwise, however, sea turtles are able to exploit their low metabolisms. They slow their metabolic rate and oxygen use so as to not require another breath for hours, allowing them to sleep for that time under the surface.
It is difficult to say for sure Mosasaurs would have slept. However, there is evidence that Mosasaurs were warm-blooded, with a relatively high metabolic rate. Consequently, I think they would have been more likely to sleep like a whale than like a turtle.
Stiggy.....is it a growth phase of the pachycephalosaur?
Stygimoloch, Dacrorex and Pachycephalosaurus are differently-sized genera of pachycephalosaur, all known from the same time and place. Work on the bone histology of the animals has shown that the known specimen of Dacrorex is an infant, Stygimoloch a juvenile, and Pachycephalosaurus an adult. This suggests that they may all be growth phases in the life of a single animal. However, it may equally mean that they are three different animals that just happen to be known from different life stages. Unfortunately, pachycephalosaur remains are generally rare, and with such small sample sizes it is difficult to satisfactorily prove this problem one way or the other.
However, that being said, it seems more likely to me that these dinosaurs are all different life stages of the same animal than that there were three very similar pachycephalosaurs living in the same time and place. Hence, I think it is best to assume this option, until more specimens let us test this more thoroughly. I do admit that this is disappointing, though, as Stygimoloch was one of my favourite dinosaurs.
Is it true that we don’t know what Carnotaurus’ feet look like? And it’s tail?
It is true that specimens of Carnotaurus that we do have do not preserve these parts of the skeleton, so we do not know exactly what they looked like. However, Carnotaurus was an Abelisaurid, and these parts of the skeleton are known from other Abelisaurs, such as Majungasaurus, allowing us to fill them in with a reasonable degree of accuracy. This suggests that the tail of Carnotaurus would have been rather unremarkable. The hind legs would have been quite stocky, but what we do have from Carnotaurus indicates that its legs would have been relatively longer than those of Majungasaurus, and so Carnotaurus would have been a more competent pursuit predator.
The question I always wanted to ask is. How come they decided to go for reptiles instead of birds for their Jurassic Park films and why are the raptors are bigger than their real-life counterpart?
Jurassic Park originally used reptiles as a model for dinosaurs partially as this was the prevailing view when the book was first written, and also as that was the public expectation of dinosaurs. Nonetheless, the book and first movie movie did draw heavily on birds for some of the depicted behaviours, so that each were quite radical when they came out. Since then, however, the Jurassic Park franchise has stuck with more reptilian dinosaurs despite the science leaving that far behind. This is probably partially to preserve continuity, and partially because the public still, unfortunately, expects and prefers their dinosaurs to be as reptilian as possible when watching movies.
Velociraptor was originally scaled-up to more resemble the size of Deinonychus by Michael Crichton when he was writing Jurassic Park. This partially followed the unusual classification of Dromaeosaurids by the palaeontologist Greg Paul, who considered Velociraptor mongoliensis and Deinonychus antirrhopus to both belong to the same genus. Jurassic Park followed this, featuring Deinonychus, but calling it Velociraptor Antirrhopus. This also explains why the featured Velociraptor skeleton was discovered by Grant in the USA, as opposed to Mongolia, where Velociraptor actually lived. However, no other palaeontologists agree with this classification, not the least because the two animals lived on separate continents, 30 million years apart! Nonetheless, Crichton decided to stick with the name Velociraptor, because he considered it more dramatic.
When it came to adapting Jurassic Park for film, the raptors were increased in size again. This was due partially to Spielberg, reportedly, being unimpressed with the size of Deinonychus. However, it was also due to the discovery of Utahraptor at around the same time – it had not yet been described and named, but there were reports of large raptor bones being found at the time that inspired the production crew of the movie.
If an eccentric millionaire was able to bring back dinosaurs and make a Jurassic Park, what is the probability of them breaking out and creating all the chaos seen in the films?
That’s a big if! However, if they did, I am sure that dinosaurs would break out every so often. How much chaos were then able to cause would be directly down to how well-prepared the millionaire had been. If they had stringent systems in place, an escaped dinosaur should be quickly containable – although their large size and strength would pose significant challenges, they would not be any more vicious or intelligent than other zoo animals. However, if they had under prepared with inadequate staff, and over reliance on untested automated systems and untrustworthy employees, then, well…
Considering how obvious this is, and I've asked this before, does the don't move thing for Tyrannosaurus sound ridiculous and is 12.5 meters the plausible maximum for the king of the Cretaceous? If a Rex went 32 mph, would it trip over?
You are correct in that vision-based eyesight for a large predator like Tyrannosaurus makes no sense at all. I am glad the series has been downplaying this since Jurassic Park.
How quickly Tyrannosaurus could run remains a strong point of contention within palaeontology. Still, most estimates do hover around the region of a running speed of 11-13 metres per second (~25 mph) – this seems sensible to me. At higher speeds the problem is not that Tyrannosaurus would necessarily fall over, but that if it did happen to trip, the head would hit the ground with such momentum that it would be fatal. Hence, it is possible that it could have briefly used such a burst of speed when closing in on prey, but it would not have used such speeds during normal locomotion or pursuit.
Are Giganotosaurus and Carcharodontosaurus considered Allosaurid or Allosauroid? And if suddenly someone brings dinosaurs to life through their original DNA, would you use frog or bird DNA, to make them as accurate as possible? And is the Jurassic Park T-Rex a bit shoehorned and shrinkwrapped?
Carcharodontosaurids such as Giganotosaurus and Carcharodontosaurus itself are Allosauroids. However, they are not also Allosaurids, but are instead more closely related to Neovenatorids: these two groups together form the Carcharodontosauria.
Were it possible to extract DNA from dinosaur fossils to revive them, I would certainly use bird DNA to plug the gaps. This would both make the resulting dinosaurs more accurate and also, due to using a more closely related animal, make it more likely that the created embryos would be viable in the first place. Unfortunately, though, it does not appear possible for DNA to survive for that long in fossils.
‘Shrink-wrapping’ is a term used to describe palaeoart that does not put enough flesh and other soft tissues on a dinosaur’s bones. As you say, the Tyrannosaurus in Jurassic Park has suffered a little bit of shrinkwrapping – the spine, shoulder blade, ribs and hips are very obvious, as are some of the edges of the skull. However, overall, most of the dinosaurs in Jurassic Park are not too bad for shrinkwrapping – the Tyrannosaurus, for example, just looks underfed – this may be as the need to create a moving 3D model means the animators will get some kind of feel for the volumes of muscle that should be present. Still, most of the dinosaurs should have lips, and the Pterosaurs in Jurassic World were shrinkwrapped to a horrifying degree, as were the heads of the Apatosaurs in the same movie.
And which parts of the Jurassic Park T-Rex would you rather fix to give nod to accuracy?
I would draw upon evidence of the integument of tyrannosaurs to make it both more accurate, but also more visually interesting. Although we know that Tyrannosaurus was mostly covered in scales, we also know that it had some regions of naked skin (and, possibly, some feathers). Furthermore, we know that Tyrannosaurus’ face was armoured by large, overlapping scales – it would be nice to include these. Despite this, I do also think that Theropods such as Tyrannosaurus would have had lips, and so would include those. The ridges on Tyrannosaurus’ head were probably for display, and it would have had good colour vision, so brightly colouring those seems both plausible and visually interesting.
In addition, drawing on the above discussion about ‘shrinkwrapping’, I would beef Tyrannosaurus up a bit, especially around the legs and tail (both related to the leg muscles, but also likely fat stores in the tail as seen in modern reptiles). I tend to like my dinosaurs to be bulky, as we tend to estimate volumes of soft tissue in animals in general from their skeletons.
How much can you rely on fused bone sutures to understand a dinosaur’s growth stage? For example, why does a juvenile T. rex have fused sutures but appears to be young when looking at its histology?
The degree of sutural fusion in a dinosaur is often used to get a rough idea of life stage although, as you say, there are many caveats. In tyrannosaurs, for example, sutures in the axial and appendicular regions of the skeleton fused very early during growth, whereas many of those in the skull never fused, even in adulthood. The fusion of sutures between bones is governed, in part, on the forces acting upon them. Consequently, the stresses place on the tyrannosaur’s back and limbs could cause them to fuse early. By contrast, the open sutures between tyrannosaur facial bones served to help absorb and redistribute shocks encountered during feeding.
With those caveats in mind, bone histology remains the best tool to understand whether a dinosaur had reached adulthood. Still, unfused sutures in certain bones are still useful in showing us whether a dinosaur was still a juvenile, even if their fusion may not necessarily indicate that they were yet an adult. For example, the unfused scapulacoracoid of the mounted skeleton of Giraffatitan means that we know it was still growing, and was not fully adult.
Even though modern evidence suggests that adult tyrannosaurs probably had no feathers, does evidence suggest that young ones may have had feathers — possibly to help regulate heat?
We know that ancestral Tyrannosauroids – such as Dilong and Yutyrannus had feathers, and so they were secondarily lost in Tyrannosaurids, perhaps due to their large size obviating the need for insulation (which, indeed, would have caused heat stress in such large animals). Consequently, I think it is very plausible that tyrannosaur chicks would have had some kind of down-like coat to help keep them warm, especially in more northerly regions of tyrannosaur habitat. Indeed, it seems probable that the small, polar Tyrannosaurid Nanuqsaurus would have retained a feathery coat in adulthood, to help it last the cold winters.
It should also be noted that, although preserved skin impressions show that Tyrannosaurids such as Tyrannosaurus and Albertosaurus were predominately scaly, we still cannot rule out the presence of small regions of feathers, whether they were relicts of their evolutionary history or growth, or even for display.
What do we know of the lifespan of dinosaurs? Elephants have a gestational period of two years. Do we know anything about length of egg carrying or incubating time? Massive dinosaurs (Titanosaurs: how long until they reach adulthood? Would it be safe to assume they lived a long time?
We can get an idea of the age of a dinosaur specimen from looking at sections of its bones, especially the long bones of the limbs. In many cases, the bones of dinosaurs bones show growth rings – like those of trees – which can be counted to establish an age. Unfortunately, some dinosaurs – especially whilst young – grew too quickly to leave rings. In other cases, remodeling of bone structure after reaching adulthood also overpinted the rings. However, even then, the texture of bone indicates how rapidly the animal was growing when it died. Comparing these between differently-sized individuals of a dinosaur species allows us to establish growth curves. This, in turn, helps to establish when a dinosaur reached sexual maturity – as indicated by a slowdown in growth as resources are diverted for reproduction – and also the age at which maximum body size was achieved.
These results show that most dinosaurs grew fast – even large dinosaurs reached sexual maturity in their teens, and maximum body size in their twenties. Maximum lifespan is harder to establish, though, as it is impossible to verify whether any particular dinosaur died of old age. However, we know of some individuals that were at least 38 years old. However, it should be noted that very few dinosaurs would have reached old age, or even full body size – most would have died relatively young, due to their violent lifestyles. Once reaching full body size, however, they would be relatively safe from attack, and maximum lifespans of 50 years or more for large dinosaurs would seem likely.
Incubation times of dinosaur eggs can be calculated by counting growth rings in the teeth of dinosaur embryos. These indicate that incubation times in dinosaurs were variable. Most dinosaur eggs probably incubated for similar timescales to those seen in modern reptiles, taking from between 3-6 months to hatch. However, those of more birdlike dinosaurs, such as Troodon, hatched more quickly (but still more slowly than in modern birds), after only ~70 days.
Even though this means Titanosaur eggs may have taken several months of burial to hatch, the low investment a mother would have to put into each egg means that she would be able to lay multiple clutches per year, each containing as many as 30 eggs, for an annual total of perhaps as many as 200 eggs in the largest species. This is a much higher reproductive rate than a modern elephant, which has to invest 22 months of pregnancy, followed by 3-5 years of devoted parental care in a single calf. The lesser pressures of egg-laying relative to pregnancy are one reason why dinosaurs were able to reach much larger sizes than mammals such as elephants.
If the Baryonyx was around today would we see them in the swamps of Florida and or Louisiana?
Evidence from the isotopic composition of the bones of Spinosaurids such as Baryonyx, as well as from fish scales preserved in the animal’s stomach, indicate that it mostly ate fish and spent a large amount of its time in or around water. The warm, swampy environment of the Everglades would seem like ideal habitat for Baryonyx – and, indeed, is not too far from the wet environment of the Wealden Formation from which it is known. No Spinosaurids are currently known from North America, but that does not mean that Baryonyx would not be able to thrive were it somehow introduced there!
A massive thank you, again, to David for working on this series with us. We’ve found it incredibly interesting – and we hope you have too! Make sure to follow David on Twitter if you aren’t already, and stay tuned to The Jurassic Park Podcast for all the latest Jurassic Park news!