The New Spinosaurus Species Is Like Nothing We’ve Ever Seen

0:00 Spinosaurus is one of the most iconic of all dinosaurs. This gigantic sail-backed fish-eating hunter would have been a formidable creature to come across back in the Cretaceous of northern Africa. Over the past decade, an intense debate has arisen over Spinosaurus and its relatives as different groups of paleontologists have reached contrasting conclusions about the lifestyle and biology of this ancient behemoth. There's no doubt that Spinosaurus was an aquatically inclined animal. Everything about its skull and tooth anatomy indicates it was adapted for catching fish, and this is supported by the discovery of its fossils in river environments, as well as isotopic analyses of its teeth showing it had a diet rich in aquatic prey. However, while one hypothesis states the Spinosaurus was a wading animal that

0:45 would stalk about in the shallows like an enormous heron and hunt for fish from above the surface, another hypothesis favored by some paleontologists is that Spinosaurus was actually an underwater pursuit hunter that would fully submerge and chase down its prey within the river. The debate about Spinosaurus's lifestyle has so far mostly centered around the single recognized species of this dinosaur that was known from fossils uncovered in Egypt and Morocco, Spinosaurus aegyptiacus. A species known as Spinosaurus maroccanus was named in the '90s as well, but has since been realized to be the same thing as aegyptiacus. But now, a team of paleontologists exploring the dinosaur fossils of Niger have discovered something very, very exciting. A second

1:31 valid species of Spinosaurus, which has all sorts of far-reaching implications for the evolution, lifestyle, and ultimate fate of this great lineage of theropod dinosaurs. The Spinosaurus saga just got a whole lot more interesting. Meet Spinosaurus maroccanus. This species was close in size and overall anatomy to Spinosaurus aegyptiacus, but with a rather extraordinary major difference. It had a large scimitar-shaped crest above its eyes. This would have been one seriously impressive beast to see in the flesh. The species name aegyptiacus reflects this remarkable anatomy, meaning astonishing in Latin. As if Spinosaurus didn't have enough exaggerated display features with its sail and tail, the whole animal, at least with maroccanus,

2:17 seems to have been one giant living billboard for showing off to others. Spinosaurus maroccanus was uncovered by a team of paleontologists who ventured into the deserts of Niger in search of a fossiliferous site first documented by French geologists in the 1950s. The location of this site had been lost in the decades since, but the researchers were able to relocate it and also went further out into the sand sea where they came across another locality that preserved some pretty significant fossils, including this new Spinosaurus species. This region, called the Gadoufaoua area, not only yielded Spinosaurus remains, but also the partial skull and skeleton of another giant carnivore, a species of Carcharodontosaurus, plus two new sauropod species which have yet to be scientifically described. I recently

3:04 spoke to one of the paleontologists who co-authored this new paper, Evan Johnson Ransom of the University of Chicago, who explained to me what the team discovered in Niger. Yeah, so originally in the 1950s, uh French geologist Hugo Soubar was was examining the geology formation in Niger and he had came across an unexpectedly large tooth that was unlike any type of theropod that was described out. And since then, this has led to Paul Sereno and colleagues to explore the Erag formation in Niger. Following this, they found essentially a couple of new bones. One bone that they thought was a tibia which would end up being the new crest of the new Spinosaurus along with a few other bones of titanosaurs along with

3:50 postcranial material of Carcharodontosaurus and many more bones of Spinosaurus marabilis. Another fossiliferous locality called Igwedi was also discovered by these paleontologists. And here they found yet more bones belonging to Spinosaurus marabilis. Altogether, they managed to recover 14 identifiable bones from these two sites, plus loads of teeth and other bits of bone they refer to the species. From these bones, the scientists were able to build up an idea of what this extraordinary creature's skull would have looked like. The most complete diagnostic specimen, the one they designated as the holotype, which means this is the definitive specimen of the species that all others are compared to, comprises much of the snout, several loose teeth, five teeth still in their sockets, and a partial crest. A couple

4:38 of other less complete specimens referred to the species preserve more of the crest, showing what the full structure would have looked like. And since the overall anatomy of the rest of the skull is comparatively similar to Spinosaurus aegyptiacus, the missing parts of the skull can be filled in using known fossils from this closely related species and other spinosaurs as a basis. So, what differentiates this species from Spinosaurus aegyptiacus? I asked Evan to explain. Yeah, so I have with me the skull of a 3D print model of Spinosaurus aegyptiacus. And one of the key things about the new specimen is that it has a relatively shallower snout. So, it's a lot more uh lower in snout height along with having a more narrow cranium, too. So,

5:24 it's a little bit more narrow and longer rostrum compared to what you would see in the robust snout material in aegyptiacus. And going further, there's also the crest as well. The crest that we found in in marabilis is relatively tall and also highly vascular. So, similar to what you would be seeing in a cassowary or even in the New Guinea fowl, too. And going forward, because this was in an inland environment, Spinosaurus maroccanus, it does have relatively greater hind limb length than Spinosaurus aegyptiacus, but this remains to be tested and also further compared with other spinosaurids like, let's say, Suchomimus and even the neotype specimen itself, too. In addition to having relatively greater neck length, as we do have some neck bones, but there's still material that

6:11 needs to be recovered from Niger, though. So, cuz I know you did a lot of kind of cranial biomechanics and such. So, do you think there's maybe a feeding difference between the species, like with the the shallower snout? Yeah, so one of the things that I have been taking a look at with maroccanus and also other spinosaurids is, of course, the snout dimensions, and we can see that with Baryonyx, they have relatively more narrow snouts. So, Irritator, even though it is missing the anterior snout, it does have a relatively more robust snout dimension, similar to what you would be seeing in aegyptiacus. And maroccanus, it's kind of an intermediate between both the Baryonyx and the spinosaurine. So, it's still relatively slender, but this was a subadult, so

6:56 there's a chance that the snout dimensions would have also increased in laterally expanded width. The geology of the sites where Spinosaurus maroccanus was uncovered indicates that it lived at approximately the same time as Spinosaurus aegyptiacus, between about 195 million years ago. It also indicates an ancient wetland riverine environment. Notably, both localities where remains of maroccanus were found are very distant from their nearest prehistoric shorelines, showing that this Spinosaurus species was living far inland, a key part of the reasoning put forward in the study for why Spinosaurus was most likely a wader rather than an underwater pursuit hunter. As extraordinary as the crest anatomy is when just looking at the fossils themselves, these structures were

7:42 probably even more insane in life. The crests that have been found so far seem to have all come from subadult individuals. If Spinosaurus maroccanus could grow to the same size as an adult Spinosaurus aegyptiacus, a scaled-up scimitar crest would then measure about 40 cm in length, nearly 16 in. And if we think that these crests were also covered by a keratinous sheath while alive, that would extend the length even further, up to more than half a meter in length, over 20 in, according to the estimate in the paper. Now, that's just silly. These giant dinosaurs might have been strutting around with half-meter long scimitars growing out of their heads. What an insane world the Cretaceous must have been. Interestingly, in all three of the crest fossils that have been discovered from the species, there is a degree of

8:29 asymmetry. This is unrelated to the effects of taphonomy, meaning it's not to do with how the bones were preserved in the ground. Instead, they would have been asymmetrical in life. It's most obvious in holotype specimen, which is deflected significantly to one side. And this condition is compared to what we see in the casques of modern-day cassowaries. Like Spinosaurus maroccanus, cassowaries also have wonky crests, and it's just how they develop. It's a cool little quirk of these animals' display features, and amazing that we can see this in Spinosaurus, too. Because only three examples of these crests have been found so far, it can't be said whether or not there's any sexual dimorphism at play here. So, we don't know if one sex perhaps had larger crests than the other. A larger sample size would be needed. However, it is

9:16 notable that the holotype individual, which is the largest individual found so far, possesses a crest that's more robust than the other two. So, with there apparently being a robust morph and a slender morph, perhaps this is a sign of sexual dimorphism. I asked Evan what he thought these remarkable crests may have been used for. So, one One the things that I take a look at with theropods crests is that typically they would have been used for um display or recognition and because it was relatively uh vascular, it's possible that Meraxes it probably would have used its tall crest more for like say individual variation, maybe for sexual display or for recognition, but one thing I should mention is that in my 2D FEA paper and also my 3D transfer paper, we found relatively low stress

10:02 magnitudes in the crests of both um Eotyrannus, even Dilophosaurus. So, it's possible that the relatively elaborate crest in these theropods would have been effective in dissipating high stress during biting. That's really interesting. So, that could be again more feeding differences between the two species with the different crest anatomies. That's really cool. The revelation of Spinosaurus maroccanus has also prompted this team of paleontologists to re-examine the evolutionary history of the entire spinosauridae family, incorporating new data from this and other recent discoveries to produce an up-to-date overview of how these dinosaurs evolved. They find that three distinct phases of spinosaurid evolution can be recognized. To begin with, the first 35 million

10:49 years of their existence, about half of their total fossil record, are so far represented only by isolated teeth recovered from Jurassic and earliest Cretaceous aged rocks. These teeth already have the characteristic anatomy of later spinosaurs. So, their fish-eating habits must have evolved during this first phase, accompanied by the various anatomical modifications that distinguish them from all other theropod dinosaurs. Throughout this phase, spinosaurs might have been quite rare animals or generally lived in environments and regions that weren't ideal for preserving their remains. This was also when the deep division between the subfamilies must have occurred with Baryonix splitting from Spinosaurines. During phase two, which makes up about 20 million years of the early Cretaceous, spinosaurids diversified

11:37 greatly, becoming the largest and most common predatory dinosaurs inhabitants that bordered the ancient Tethys Sea. To the south of the sea, Baryonychine species such as Suchomimus arose in Africa, and the spinosaurine Irritator evolved in Brazil. Meanwhile, to the north, an array of Baryonychine's appeared in Europe, and spinosaurines occupied Asia, represented from Laos. This phase may also have witnessed the presence of coexisting spinosaurines and Baryonychines, with evidence for both lineages occupying the same habitats in Iberia and possibly in Thailand as well. The final phase of spinosaurid evolution lasted about 15 million years, when the subset of spinosaurines called Spinosaurini appeared. These animals survived only on

12:24 the southern side of the Tethys Sea, represented by the two Spinosaurus species in Africa, and Oxalaia plus another unnamed spinosaurine in Brazil. By this point in time, the equatorial Atlantic Gateway had opened, and Africa and South America were separated by a deep water strait. The last phase marked the appearance of increased piscivorous specializations in the remaining spinosaurines, including more modifications to the snout and a tighter S shape of the neck, with enhanced downward flexion. This is also when the enormous exaggerated spines of the back and tail appeared. Here's Evan talking about some of the major differences that have been found between the spinosaurines and Baryonychines. Yeah, so one of the things we can talk about with the Baryonychines and spinosaurines

13:09 is that the Baryonychines, they have a relatively greater tooth count, but they're a little bit more narrow than what you would be seeing in the spinosaurines, which are more robust and also lack the serrations. So, this would indicate that spinosaurines were putting in a lot more heavily processing of food. In addition to that, they also have relatively more robust or wider expanded snouts compared to the Baryonyx. So, this can probably give us an idea that spinosaurines, they were more like general predators, something that we do see in Demore et al. 2024, which I was a co-author on, where we took a look at alveolar space and tooth dimensions in spinosaurids with other crocs.

13:54 The end of the spinosaurinae subgroup and of spinosaurids as a whole occurred when a rapid sea level change took place about 94 and 1/2 million years ago, flooding low-lying continental regions and forming a shallow sea across the Sahara. A rise in global temperatures also led to a turnover in marine life, and on land, spinosaurs plus a few other dinosaur lineages went extinct. Of course, one of the big questions many people have when a new spinosaur paper comes out is how does this contribute to the great spinosaurus war? The controversy over whether spinosaurus hunted by wading through shallows like a giant heron or by submerging and propelling itself along underwater has raged for more than a decade now. So, what does spinosaurus mirabilis mean for

14:40 the debate? Well, firstly, one of the most apparent revelations from this discovery is that a large scimitar-shaped crest on the forehead is probably not going to do this animal any hydrodynamic favors if it really was swimming underwater, especially if these crests are frequently asymmetrical, too. The presence of this exaggerated crest also casts some significant doubt on the claimed function of the long neural spines on the tail of spinosaurus aegyptiacus. When this part of the dinosaur's anatomy was first described back in 2020, it was hypothesized that the tail functioned as a propulsive organ for swimming underwater, kind of like the tail of a giant newt. However, many researchers have since doubted this interpretation, instead favoring the idea that the tail sail was probably

15:26 also for visual display paired with the sail on the back. Now, with the discovery of this massive scimitar crest on the head, it further highlights that these dinosaurs were engaging in a lot of visual signaling. So, it seems more likely that the primary function of the tail was also probably for display rather than aquatic locomotion. Secondly, the location of the fossils in an inland river system suggests these animals were not underwater pursuit predators on their way to becoming fully secondarily aquatic, as has been inferred by other studies. Large-bodied vertebrate animals that have become secondarily aquatic tend to undergo this transition in coastal areas, near seas or oceans, and only later invade freshwater systems. So, Spinosaurus marabilis living very far inland is more

16:13 consistent with them being riverbank hunters or shallow water waders, not specialized subaqueous foragers. Furthermore, this new study also undertakes what's known as a principal components analysis, or PCA, to determine which animals the body and skull proportions of Spinosaurus are most similar to. Since form generally fits function, this can tell us how Spinosaurus most likely lived. I asked Evan to run through the specific measurements taken from Spinosaurus and the other animals in the analysis, and what the results tell us about how Spinosaurus lived. Yeah, so what I did was that I was interested in taking a look at the cranial dimensions. So, this included getting the overall cranium length along with cranial height, and we

16:59 also measured the occipital width. So, this is going to be important as this is going to serve as attachments for neck muscles. In addition to that, I also took relative snout height as well as snout width. And for neck length, it was the total summation of the centrum of the cervical vertebrae. In addition to that, I also measured the hindlimb. So, for total hindlimb length, this was measuring the length of the femur, the tibia, and also metatarsals. And this resulted in a principal component analysis. Now, one of the things I should probably bring up is that with PC1, body size was a major factor in PC1 because we have essentially large theropods along with crocodylians and birds. So, this definitely was going to be a a

17:45 major size component for us. But, when we took a look at the other PC components like PC2 and PC3, this resulted in a relatively greater expanse in being able to evaluate just how different spinosaurids were from other theropods. So, if you see in this plot right here, we have a lot of the more terrestrial theropods like Tyrannosaurus Ceratosaurus and Allosaurus. They're sitting with a lot of the more carnivorous birds like vultures and condors and secretary birds, and also the shoebill stork. The one thing I should mention is that the shoebill stork, it is it is a wading bird that we that you normally would find in the shorelines, but does have relatively wider snout, too. So, something that you would see in a lot of

18:31 the more terrestrial theropods. But, spinosaurids, we have them sitting essentially with all of these relatively long-necked shorebirds. So, this includes the herons, the storks, the ibis, along with the anhinga and cormorant. But, they are far away from a lot of the aquatic pursuit birds. So, your penguins and also your crocodylians, too. And this is actually an important factor because this can probably give us an idea as to what the overall body plan for these theropods were. So, basically spinosaurs are their own thing, but potentially most most likely waders. Yes, most likely waiters who would have frequ- who would have frequented on both land and also in

19:18 the water. Not necessarily deep-sea divers. Um and so the discovery location of the species as well was really far inland in a terrestrial basin. So that also contributes to our understanding. Yes, so because it was found near an inland environment as opposed to being near an open water environment, this would suggest that Spinosaurus marabilis it probably would have been more like essentially a giant stork or heron. And coupled with its relatively long neck, its narrow cranium, along with having neck muscles that would have helped us facilitate uh dorsal ventral movement of the head and neck, and long legs for wading, it would have been more like essentially a giant heron from hell. That's a great way of putting it. They must have been such awesome animals. I really wish could have seen a

20:03 Spinosaurus in the flesh. Who knew? Spinosaurus marabilis is a truly astonishing new discovery, and it's a tremendously exciting new chapter in the study of these dinosaurs. I have no doubt that this is not the end of the Spinosaurus wars though. I look forward to seeing what's comes next. You can be sure that 7 Days of Science will be here to keep you updated. I'd like to say a huge thank you to Evan Johnson Ransom for taking the time to talk to me about this amazing new study, and congratulations on the publication. I'll link Evan's social media pages down below. Please do go follow him for some awesome paleontology content and to learn more about his exciting research. Here's Evan talking about some of the cool stuff he's currently working on. So what I'm currently doing right now is that I am looking at reconstructing the

20:48 neck musculature and jaw muscles of spinosaurids, and also non-spinosaur theropods like T-Rex. And so what I'm doing is that I'm essentially being able to estimate the center of mass or head volume to be able to see how much inertia or a proxy for agility these theropods were be able to generate during various forms of feeding moment. Spinosaurids, they do have relatively greater They're more agile when it comes to bringing their heads and necks forward, though. So, and this is something that we would see in a lot of shorebirds. So, you could imagine spinosaurids, of course, being once again a giant L heron. But, with tyrannosaurids, they have relatively greater head mass, though. And also, they have a laterally

21:33 expanded head with neck muscles that would be more situated for tearing, or in this case, lateral shaking of food sideways. So, think of them as essentially like a mix between the birds of prey like owls and also crocodilians. I hope you enjoyed the 7 Days of Science special feature all about the Spinosaurus news. And do be sure to subscribe to the channel to keep up-to-date with all the latest science discoveries. Thanks for watching, and we'll see you next time.