(CNN) The so-called Frankenstein dinosaur is the missing link connecting plant-eating dinosaurs such as the Stegosaurus to a group including carnivorous ones such as the Tyrannosaurus rex, scientists have suggested.

The vegetarian dinosaur walked the Earth around 150 million years ago and is officially known as the Chilesaurus. It initially confused scientists because of its strange physical characteristics, apparently drawn from two groups of dinosaurs that were thought to be separate.

Originally discovered in South America, the Chilesaurus has the head of a carnivore but flat teeth suited to grinding plants.

"Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody," said Matthew Baron, a Ph.D. student in the University of Cambridge's department of earth sciences and joint first author of a new study on the dinosaur published Wednesday.

The researchers, from Cambridge and London's Natural History Museum, analyzed more than 450 anatomical characteristics of early dinosaurs to find the right place for the Chilesaurus in the dinosaur family tree.

Read More </s> The legendary Bigfoot is often described as the "missing link" between apes and man, but the Chilesaurus has an edge on Bigfoot: it is the missing link between herbivore dinosaurs and their carnivorous brethren.

In a new study done by the University of Cambridge, Chilesaurus, which lived 150 million years ago, scientists now believe the dinosaur is an early member of the "Ornithischia," a "bird-hipped" group that includes dinosaurs such as the Stegosaurus and Iguanadon.

Researchers found that the Chilesaurus has the same inverted hip structure of the Ornithischia group, which aids in complex digestive systems. But it also lacks the beak Ornithischia dinosaurs used for eating.

NEWFOUND DINOSAUR LOOKS LIKE THE CREEPY LOVE CHILD OF A TURKEY AND AN OSTRICH

“Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody,” said Matthew Baron, a doctoral student in Cambridge University's Department of Earth Sciences and the paper’s joint first author, in a statement.

The dino, which has been described as ‘Frankenstein’s monster,’ confused scientists because it had a head that "resembles that of a carnivore, but it has flat teeth for grinding up plant matter," according to a press release, discussing the findings.

The researchers analyzed more than 450 anatomical characteristics of early dinosaurs to come up with the placement.

Chilesaurus originally belonged to the group Theropoda, ‘lizard-hipped’ group of dinosaurs which includes Tyrannosaurus rex.

"Before this, there were no transitional specimens – we didn’t know what order these characteristics evolved in,” Baron added. “This shows that in bird-hipped dinosaurs, the gut evolved first, and the jaws evolved later – it fills the gap quite nicely.”

“Chilesaurus is one of the most puzzling and intriguing dinosaurs ever discovered,” said co-author Professor Paul Barrett of the Natural History Museum in London. “Its weird mix of features places it in a key position in dinosaur evolution and helps to show how some of the really big splits between the major groups might have come about.”

The latest findings were published in the journal Biology Letters. </s> A dinosaur we've only known about for a couple of years could be the missing link between plant-eating dinosaurs and members of the theropod group, including carnivores like Tyrannosaurus Rex and Velociraptor.

That's based on a new analysis of the Chilesaurus dinosaur – first identified in 2015 from a fossil find in Chile, it's intrigued researchers ever since with its odd mix of physical characteristics.

Not only does Chilesaurus bridge a rather large gap between the two biggest dinosaur groups, it also gives us clues about how that gap might have been created, according to the team from the University of Cambridge and the Natural History Museum in the UK.

"Chilesaurus is one of the most puzzling and intriguing dinosaurs ever discovered," says one of the researchers, Paul Barrett of the Natural History Museum.

"Its weird mix of features places it in a key position in dinosaur evolution and helps to show how some of the really big splits between the major groups might have come about."

The dinosaur family tree may need rewriting. Credit: University of Cambridge

The dinosaur in question has a small skull, long neck, and a body measuring about 3 metres (or 10 feet). It's thought to have lived about 145 million years ago during the Jurassic Period.

The team analysed more than 450 anatomical characteristics of Chilesaurus to try and place it in the right part of the dinosaur family tree.

The two major dinosaur groups that Chilesaurus could bridge are the 'lizard-hipped' Theropoda group, including Tyrannosaurus rex, and the 'bird-hipped' Ornithischia group, including the likes of Triceratops.

It was originally thought that Chilesaurus belonged in the lizard-hipped group, but the new study suggests it's a very early member of the bird-hipped group instead.

Chilesaurus has inverted, bird-like hips, but it doesn't have the distinctive, bird-like beak for eating like all the other Ornithischia dinosaurs, such as Stegosaurus or Iguanodon, and that's what makes it so important to paleontologists.

And while its head resembles that of a carnivore, it has flat teeth best suited to grinding up plants. It's a mixture of mysteries.

"There was a split in the dinosaur family tree, and the two branches took different evolutionary directions," says one of the team, Matthew Baron from the University of Cambridge.

"This seems to have happened because of change in diet for Chilesaurus. It seems it became more advantageous for some of the meat-eating dinosaurs to start eating plants, possibly even out of necessity."

If Chilesaurus really is an ornithopod rather than a theropod, then it can help us understand how this group of dinosaurs developed. Based on the team's analysis, it looks like the gut of this dinosaur evolved before the jaw, for example.

And it means ornithopods and theropods are more closely related in the dinosaur family tree than previously thought. In other words, they had common ancestors, rather than evolving separately, and Chilesaurus is one of the earliest keys to that.

In the end it turns out that a dinosaur that had been seen as something of a Frankenstein's monster is actually one of the most significant we've identified so far.

"Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody," adds Baron.

The findings have been published in Biology Letters. </s> A bizarre dinosaur which looked like a raptor but was, in fact, a vegetarian may be the ‘missing link’ between plant-eating dinosaurs and carnivores such as the dreaded Tyrannosaurus rex, scientists say. Researchers from the University of Cambridge and the Natural History Museum in the UK used a comprehensive dataset to analyse over 450 anatomical characteristics of early dinosaurs and correctly placed the creature, known as Chilesaurus, in the dinosaur family tree. The results, published in the journal Biology Letters, suggest that Chilesaurus effectively fills a large gap between two of the major dinosaur groups, and shows how the divide between them may have happened.Chilesaurus, which was discovered in southern Chile, was first described in 2015. It lived during the Late Jurassic period, about 150 million years ago, and has an odd collection of physical characteristics, which made it difficult to classify.

For example, its head resembles that of a carnivore, but it has flat teeth for grinding up plant matter. “Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody,” said Matthew Baron, a Ph.D. student at Cambridge. Earlier research suggested that this peculiar dinosaur belonging to the group Theropoda, the ‘lizard-hipped’ group of dinosaurs that includes Tyrannosaurus, but the new study suggests that it was probably a very early member of a completely different group, called Ornithischia. This shuffling of the dinosaur family tree has major implications for understanding the origins of Ornithischia, the ‘bird-hipped’ group of dinosaurs that includes Stegosaurus, Triceratops, and Iguanodon.

The bird-hipped dinosaurs have several common physical traits: the two most notable of these are an inverted, bird- like hip structure and a beak-like structure for eating. The inverted hips allowed for bigger, more complex digestive systems, which in turn allowed larger plant-eaters to evolve, researchers said. While Chilesaurus has a bird-like hip structure and has flat teeth for grinding up plants, it does not possess the distinctive ‘beak’ of many other bird-hipped dinosaurs, which is what makes it such an important find, they said. “Before this, there were no transitional specimens – we did not know what order these characteristics evolved in,” said Baron.

“This shows that in bird-hipped dinosaurs, the gut evolved first, and the jaws evolved later – it fills the gap quite nicely,” he said. “Chilesaurus is one of the most puzzling and intriguing dinosaurs ever discovered,” said Professor Paul Barrett of the Natural History Museum. “Its weird mix of features places it in a key position in dinosaur evolution and helps to show how some of the really big splits between the major groups might have come about,” said Paul. </s> A bizarre-looking dinosaur discovered by a young boy in Chile may be the missing link showing how members of one major dinosaur lineage evolved into a completely new dinosaur group, a new study finds.

Researchers in the United Kingdom say the species, dubbed Chilesaurus diegosuarezi, explains how some theropods, mostly meat-eating, bipedal dinosaurs, evolved into the herbivorous, long-necked ornithischians.

Previously, it was unclear how the "ornithischian group just suddenly appeared and became this well-adapted herbivorous group," said the study's co-lead researcher, Matthew Baron, a doctoral student of paleontology at the University of Cambridge in England. "There was no intermediate step. This is the first one we've found." [See Photos of the Missing Link, Chilesaurus diegosuarezi]

If future research confirms this finding, this would make Chilesaurus the earliest member of Ornithischia, a group that includes the armored dinosaurs, such as Stegosaurus and Ankylosaurus, as well as horned dinosaurs, such as Triceratops.

But not everyone is on board with this interpretation. Rather, more "grunt work" is needed to determine Chilesaurus' true identity, said Thomas Carr, an associate professor of biology at Carthage College in Wisconsin and a vertebrate paleontologist. Carr was not involved in the study.

This isn't the first time Chilesaurus has turned heads. In 2010, 7-year-old Diego Suárez, the son of two geologists, found the 145-million-year-old beast in southern Chile's Toqui Formation.

After Diego found the first specimen, excavations in Chile yielded more than a dozen Chilesaurus individuals, including four complete skeletons that ranged from turkey-size young dinosaurs to nearly 10-foot-long (3 meters) adult dinosaurs. But despite the abundance of fossils, Chilesaurus' anatomy was a real head-scratcher.

The creature looked like a mixture of lineages. It had the long neck, small skull and clunky feet of a sauropodomorph (a group of long-necked, herbivorous dinosaurs with lizard-like hips); the beak, teeth and pubic bone of an herbivorous, bird-hipped ornithischian; and the bipedal stance, robust forelimbs and ilium (the upper part of the pelvic bone) of a meat-eating theropod.

To determine where Chilesaurus fit in the dinosaur family tree, the South American researchers looked at four data sets to compare the dinosaur's features with those of theropods, mainly from the Jurassic and Cretaceous periods, as well as with sauropodomorphs. In the end, they deemed Chilesaurus an enigmatic plant-eating theropod, a relative of Tyrannosaurus rex and the fearsome Velociraptor, according to a 2015 study published in the journal Nature.

However, not everyone was satisfied with Chilesaurus' classification as a theropod. Earlier this year, Baron and his colleagues stunned dinosaur researchers when they published a study revising the dinosaur family tree. According to their analyses, theropods and ornithischians were more closely related than previously thought.

Baron wanted to see where Chilesaurus fit on the new family tree. So he reached out to Fernando Novas, a paleontologist at the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires, Argentina, who was the lead researcher on the 2015 Nature study.

Novas provided data on Chilesaurus to Baron and study co-lead researcher Paul Barrett, a paleobiologist at the Natural History Museum in London. Once Baron and Barrett had Chilesaurus' information, they plugged it into their enormous data set, which has data on the earliest dinosaurs on record. [Gory Guts: Photos of a T. Rex Autopsy]

"[Chilesaurus] came out as basically the first diverging member of one of the major groups, which is a position that had never been suggested before," Baron told Live Science. "It was a bit of a surprise."

However, evolution is a long, complicated process. There are ornithischians that are older than the Late Jurassic Chilesaurus, but they likely evolved from earlier theropods, Baron said. The fossils of these older, transitional creatures have yet to be found, he said.

"More and more evidence is now appearing that the ornithischian group might just be entirely Jurassic and Cretaceous, that they weren't present in the first period of dinosaur history [the Triassic]," he said.

It's difficult to say which interpretation is correct — that is, whether Chilesaurus is a theropod or an early member of Ornithischia, Carr said.

"Having read these works side by side, I can understand why the [2015 researchers] thought what they thought: The evidence is convincing that it's a theropod," Carr told Live Science. "[But] this new paper is just as convincing that it's an ornithischian."

There's only one way out of this conundrum, Carr said: "All of these data sets have to be combined" so researchers can determine, once and for all, where Chilesaurus fits — a task that can't be completed unless all of the relevant and available data from the Mesozoic is used.

Even though the family trees are different, it's possible to combine the data sets of the early dinosaurs that Baron used and the Sauropodomorpha and later theropod data sets that Novas and his colleagues used, Carr noted.

"It does take a lot of work, but in the end, what you get is a data set that includes all of the relevant characters from all of the relevant analyses," he said. Only then can researchers "get the single truth, the historical truth of the universe as it happened," Carr said.

Baron accepted the critique in stride. "That's genius because that's exactly what we need to do," Baron said. "And that's exactly what I am doing at the [moment]."

Combining data sets is arduous work and could take four or five years to complete, Baron said. But the end result would shine a light on dinosaur evolution, which is a valuable step forward because "we actually are finding we know less and less about dinosaur evolution," Baron said. [Photos: Newfound Tyrannosaur Had Nearly 3-Inch-Long Teeth]

If that's the case, then the discussion on Chilesaurus' relationships has just begun, Novas told Live Science. "However, I welcome the novel interpretation by Baron and Barrett, because it promotes a necessary debate on poorly known aspects of dinosaur evolution as a whole," Novas said.

The new study was published online today (Aug. 16) in the journal Biology Letters. </s> A 'Frankenstein's monster' dinosaur may be the missing link between two major dinosaur groups - plant eaters and predators such as T-rex.

The bizarre dinosaur, called the Chilesaurus, was vicious like a raptor but was in fact a vegetarian.

In a new study, researchers suggest that some Chilesaurus started eating meat while others started eating plants, leading to a split between the two groups.

The findings have allowed experts to correctly place the creature in the dinosaur family tree and map the evolution of certain traits.

Chilesaurus, which was discovered in southern Chile, was first described in 2015.

It lived during the Late Jurassic period, about 150 million years ago, and has an odd collection of physical characteristics, which made it difficult to classify.

For example, its head resembles that of a carnivore, but it has flat teeth for grinding up plant matter.

Researchers from the University of Cambridge and the Natural History Museum now suggest Chilesaurus shows how the divide between two major dinosaur groups may have happened.

'Chilesaurus almost looks like it was stitched together from different animals, which is why it baffled everybody,' said Matthew Baron, a PhD student in Cambridge's Department of Earth Sciences and the paper's joint first author.

Earlier research suggested that this peculiar dinosaur belonging to the group Theropoda - the 'lizard-hipped' group of dinosaurs that includes Tyrannosaurus.

But the new study suggests that it was probably a very early member of a completely different group, called Ornithischia.

This shuffling of the dinosaur family tree has major implications for understanding the origins of Ornithischia - the 'bird-hipped' group of dinosaurs that includes Stegosaurus, Triceratops and Iguanodon.

The bird-hipped dinosaurs have several common physical traits: the two most notable of these are an inverted, bird-like hip structure and a beak-like structure for eating.

The inverted hips allowed for bigger, more complex digestive systems, which in turn allowed larger plant-eaters to evolve.

While Chilesaurus has a bird-like hip structure, and has flat teeth for grinding up plants, it does not possess the distinctive 'beak' of many other bird-hipped dinosaurs, which is what makes it such an important find.

'Before this, there were no transitional specimens – we didn't know what order these characteristics evolved in,' said Mr Baron.

'This shows that in bird-hipped dinosaurs, the gut evolved first, and the jaws evolved later – it fills the gap quite nicely', he said.

'Chilesaurus is one of the most puzzling and intriguing dinosaurs ever discovered,' said co-author Professor Paul Barrett of the Natural History Museum.

'Its weird mix of features places it in a key position in dinosaur evolution and helps to show how some of the really big splits between the major groups might have come about.'

'There was a split in the dinosaur family tree, and the two branches took different evolutionary directions,' said Dr Baron.

'This seems to have happened because of change in diet for Chilesaurus. It seems it became more advantageous for some of the meat eating dinosaurs to start eating plants, possibly even out of necessity.'

Earlier this year, the same group of researchers argued that dinosaur family groupings need to be rearranged, re-defined and re-named.

In a study published in Nature, the researchers suggested that bird-hipped dinosaurs and lizard-hipped dinosaurs such as Tyrannosaurus evolved from a common ancestor, potentially overturning more than a century of theory about the evolutionary history of dinosaurs.

Although their dataset has already thrown up some surprising results, the researchers say that as it currently analyses only early dinosaurs, there are probably many more surprises about dinosaur evolution to be found, once characteristics of later dinosaurs are added. </s> A missing link between plant-eating dinosaurs and meat-eaters such as the Tyrannosaurus rex may have been found, suggests a new study from the University of Cambridge and the Natural History Museum.

After analyzing more than 450 anatomical characteristics of early dinosaurs, the researchers found that Chilesaurus — first described in 2015 — fills the gap between the two groups.

Chilesaurus, which lived 150 million years ago in the Late Jurassic Period, was a puzzling dinosaur that looked like a meat-eating raptor, yet was a herbivore.

"It was so mysterious," Matt Baron, lead author and a PhD student from Cambridge University, told CBC News. "When it was first published in 2015 it really caused a stir, because it was so unusual, a Frankenstein dinosaur. It was made up of such a weird combination of features."

The head of the Chilesaurus resembles that of a carnivore. However, its hip structure was more like Ornithischia (which means "bird-hipped" in Greek). It also had flat teeth for grinding plant material. Making things more puzzling, it had short forelimbs like the allosaurus, a carnivore. However, it lacked claws and instead had stump-like fingers.

"Most of the time with fossils and particular dinosaurs, you can look at bones from the animal and there are certain features of the bone that you can look at and say, 'This belongs to this group because it has this and this,'" Baron said. "With Chilesaurus, if you were to pick up any bone from its body and look at it individually, you'd be forgiven for thinking the bones belonged to a whole range of animals.

"It looked like it had been stitched together from lots of different animals. It was baffling. It was really weird," Baron said.

Baron was part of a team that sought to reclassify all dinosaurs earlier this year in an effort to account for the advances and discoveries made since the first dinosaur family tree was laid out in 1888. It was this project that led to the findings on Chilesaurus.

Chilesaurus possessed both carnivorous and herbivorous dinosaur traits, Baron said, because it was adapting to a changing planet, one that was developing lush green landscapes with plenty of plants to consume.

A body that digests plant matter is vastly different from one that needs to digest meat, Baron said. One key difference is a larger gut, a reason for wider hips.

Baron said that the findings aren't just a window on the past, but also help us to better understand how animals adapt to a changing world.

"We can learn a lot from the way in which they adapted and changed to a changing environment," Baron said. "Given the Earth is changing so much right now, it's good to have things in the fossil record that we can look at and can say, 'Oh, well look: this is one of the ways in which life responded to this change."

Baron acknowledged that there's likely to be pushback from the researchers' findings. Fernando Novas, who first described Chilesaurus in 2015, has expressed some concerns.

In an email statement about the findings, Novas said that Baron and his co-author Paul Barrett overlook strong similarities the dinosaur shares with meat-eating Theropods, including various bone structures.

"I guess the discussion on Chilesaurus relationships [has] just begun, and the years to come will testify fluctuating interpretations on the early dinosaur diversification." he said. "However, I welcome the novel interpretation by Baron and Barrett, because it promotes a necessary debate on poorly known aspects of dinosaur evolution as a whole."
• This newly discovered armoured dinosaur had to hide from bigger, meaner </s> SALT LAKE CITY — Turns out, arid southern Utah was once a lush, prehistoric delta and the hunting grounds of a mule-deer-sized predecessor to the well-known 10-ton apex predator, Tyrannosaurus rex.

Details of the oldest Cretaceous Tyrannosaur species yet discovered in North America were published Thursday in the journal Communications Biologyby North Carolina State University paleontologist, and University of Utah graduate, Lindsay Zanno.

Moros intrepidus — "harbinger of doom" — according to Zanno's paper, is 96 million years old and helps fill in a sizeable gap in the fossil record from the 80-million-year-old giant made famous by movies like "Jurassic Park" to evidence of much earlier related species' dating back 150 million years. While scientists believe T. rex rose to become the alpha predator of the late Cretaceous period, for the 6-foot, 170-pound moros roaming Emery County back in the day, things were much different.

"With a lethal combination of bone-crunching bite forces, stereoscopic vision, rapid growth rates, and colossal size, tyrant dinosaurs reigned uncontested for 15 million years leading up to the end-Cretaceous extinction – but it wasn’t always that way,” Zanno said in a statement. “Early in their evolution, tyrannosaurs hunted in the shadows of archaic lineages such as allosaurs that were already established at the top of the food chain.”

The 70 million year gap in the fossil record for North American tyrannosaurs has left scientists scratching their heads about how the now-infamous tyrant dinosaur evolved to surpass and dominate other predators of the time. Zanno chose her Utah site specifically because of its fossil evidence from this missing era and has been working in the area for over a decade. She's also had a previous discovery from a nearby site of a giant meat-eating dinosaur called Siats meekerorum_._

Zanno said while her latest discovery was a diminutive creature for the times, it already had a combination of traits that would help propel it up the ladder of dominance.

“Moros was lightweight and exceptionally fast,” Zanno said. “These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator. It could easily have run down prey, while avoiding confrontation with the top predators of the day."

“Although the earliest Cretaceous tyrannosaurs were small, their predatory specializations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level and shrinking ranges restructured ecosystems at the beginning of the late Cretaceous.

“We now know it took them less than 15 million years to rise to power.” </s> A team of researchers, including UNM Honors College Professor Jason R. Moore, has found a new species of tyrannosaur dinosaur — the most popular of the prehistoric creatures.

After the fossils were pulled out of the muddy banks of a Montana river, the team was able to analyze the texture of the facial bones of the new species. The findings suggest that the face of tyrannosaurs was covered in a scaly protective layer with a high degree of tactile sensitivity, similar to crocodiles.

“Being a tyrannosaur, they had really small arms,” says Moore. “They wouldn’t be able to interact with their environment with their hands the way mammals do — find food, build nests, tend to eggs and young. In order to do these things, Daspletosaurus needed to use its feet or head. The discovery and analysis of the tyrannosaur shows that the dinosaur had a developed face sensitivity similar to the sensitivity in our finger tips, suggesting it could use its snout for all those complex ecological interactions, similar to the way crocodiles do today.”

An investigation by a team of scientists from Wisconsin, Australia, Louisiana, Montana and New Mexico has identified and named the new species of the tyrannosaur clan: Daspletosaurus horneri – “Horner’s Frightful Lizard.”

The species is named for the renowned dinosaur paleontologist, John “Jack” R. Horner, formerly curator at the Museum of the Rockies (MOR) in Bozeman, Montana. The tyrannosaur’s name honors his discoveries of numerous dinosaur fossils and his mentorship of so many students that launched them on to accomplished scientific careers. The name-bearing specimens are stored in the research collections of the MOR.

The fossil resources of Montana, where the new tyrannosaur was found, are central to studies of dinosaur evolution.

“Montana, similar to many Rocky Mountain states, has lots of rock exposed at the right time and right environment to contain dinosaurs,” says Moore. “The fossils are found preserved in ancient river channels and flood plains. If you know what you’re looking for, they are widespread.”

The research is led by Thomas Carr of Carthage College’s Department of Biology in Wisconsin, an expert on the evolution and growth of Tyrannosaurus rex and its closest relatives, collectively called tyrannosaurs.

The family tree

 In addition to adding a new species to the tyrannosaur family tree, the team’s research provides new information about the mode of evolution and life appearance of tyrannosaurs, specifically the face.

This latest study, published in Nature Publishing Group’s Scientific Reports, found evidence for a rare, nonbranching type of evolution in tyrannosaurs and that tyrannosaurs had scaly, lipless faces and a highly touch-sensitive snout.

“Daspletosaurus horneri was the youngest, and last, of its lineage that lived after its closest relative, D. torosus, which is found in Alberta, Canada,” says Carr. “The geographic proximity of these species and their sequential occurrence suggests that they represent a single lineage where D. torosus has evolved into D. horneri.”

Moore elaborated, “One of the difficulties in demonstrating this style of evolution is establishing that the different species don’t overlap in time. The new radiometric dates we measured help support this temporal separation between D. torosus and D. horneri.”

The research confirms that the ages of the two species shows that the evolution of the dinosaur was slow—happening over a span of 2.3 million years.

The team’s work literally changes the face of tyrannosaurs, which they found was covered by a lipless ‘mask’ of large flat scales and extensive patches of armor-like skin. This conclusion results from comparison of tyrannosaur skulls with those of crocodylians, birds and mammals, and earlier work by other researchers who had matched bone texture with different types of skin covering.

Jayc Sedlmayr, professor at the Louisiana State University Health Sciences Center New Orleans, explained, “Much of our research … was generated from lab based comparative anatomy, where you get arms deep in ‘blood and guts’ dissecting birds—living dinosaurs and crocodilians—their closest living relatives.”

The crocodile connection 

 “It turns out that tyrannosaurs are identical to crocodylians in that the bones of their snouts and jaws are rough, except for a narrow band of smooth bone along the tooth row,” explained Carr. “We did not find any evidence for lips in tyrannosaurs: the rough texture covered by scales extends nearly to the tooth row, providing no space for lips.”

“However, we did find evidence for other types of skin on the face, including areas of extremely coarse bone that supported armor-like skin on the snout and on the sides of the lower jaws. The armor-like skin would have protected tyrannosaurs from abrasions, perhaps sustained when hunting and feeding.”

The researchers found that, like in crocodylians, the snout and jaws of the tyrannosaurs are penetrated by numerous small nerve openings, allowing hundreds of branches of nerves to innervate the skin, producing a sensitivity similar to that of human fingertips.

This sensitivity is part of a bigger evolutionary story, explained Sedlmayr. “The trigeminal nerve has an extraordinary evolutionary history of developing into wildly different ‘sixth senses’ in different vertebrates, such as sensing magnetic fields for bird migration, electroreception for predation in the platypus bill or the whisker pits of dolphins, sensing infrared in pit vipers to identify prey, guiding movements in mammals through the use of whiskers, sensing vibrations through the water by alligators and turning the elephant trunk into a sensitive ‘hand’ similar to what has been done to the entire face of tyrannosaurs.”
Researchers from the University of Cambridge suggest that the Chilesaurus may be the so-called "missing link" between the Stegosaurus and the Tyrannosaurus.