Tag Archives: theropod

Rare dinosaur footprint fossils give clues into a forgotten era

Around 170 million years ago, a group of long-necked sauropods was taking a stroll along a muddy, shallow lagoon in what is now the north-east coast of the Isle of Skye. Using a mixture of modern techniques and good old-fashioned paleontology, researchers have now found and analyzed these footprints, gaining new insight into this ancient period.

The Isle of Skye used to be a dinosaur haven. Image credits: Avery Ng.

Lying just off the coast of Scotland, the Isle of Skye has been inhabited since the Mesolithic period, and its rich history includes a time of Norse rule and a long period of domination by the legendary Clan MacLeod. But before that (way before that), it was a coastal lagoon inhabited by several species of dinosaur.

Researchers from the University of Edinburgh, Staffin Museum, and Chinese Academy of Sciences found 50 footprints in a tidal area at Brothers’ Point, in one of Skye’s numerous small peninsulae. In addition to numerous isolated footprints, researchers identified two pathways which feature footprints from both sauropods and therapods (older cousins of Tyrannosaurus Rex).

Sauropod footprint discovered in Scotland. Image credits: Paige dePolo.

The finding is particularly significant since the footprints have been dated to the mid-Jurassic. Middle Jurassic dinosaur fossils “are exceedingly rare, but new discoveries from the Isle of Skye, Scotland, are beginning to fill this gap,” researchers write. Paige dePolo, who led the study, commented:

“This tracksite is the second discovery of sauropod footprints on Skye. It was found in rocks that were slightly older than those previously found at Duntulm on the island and demonstrates the presence of sauropods in this part of the world through a longer timescale than previously known. This site is a useful building block for us to continue fleshing out a picture of what dinosaurs were like on Skye in the Middle Jurassic.”

Studying Skye isn’t easy — the site’s location in a tidal area made the task extremely difficult. Researchers had to use drone photographs to create a map of the site, in addition to a paired set of cameras and tailored software they used to model the tracks. This allowed the team to assess the shape and orientation of the toes, as well as the presence of claws

But it was well worth it. Skye has already yielded a trove of valuable findings and Dr. Steve Brusatte, of the University of Edinburgh’s School of GeoSciences, who led the field team, says there might be even more in store.

“The more we look on the Isle of Skye, the more dinosaur footprints we find. This new site records two different types of dinosaurs — long-necked cousins of Brontosaurus and sharp-toothed cousins of T. rex — hanging around a shallow lagoon, back when Scotland was much warmer and dinosaurs were beginning their march to global dominance,” said Brusatte.

Journal Reference: dePolo et al. A sauropod-dominated tracksite from Rubha nam Brathairean (Brothers’ Point), Isle of Skye, Scotland. https://doi.org/10.1144/sjg2017-016

A fabulous T-Rex. Credit: Wikimedia Commons

Flamboyant dinosaur headgear linked with outrageously big carnivorous dinosaurs

A fabulous T-Rex. Credit: Wikimedia Commons

A fabulous T-Rex. Credit: Wikimedia Commons

Large carnivorous dino species like Tyrannosaurus or Allosaurus were among the biggest predators to ever walk on the face of the planet. They also had the ‘bling’ to match their size, according to a group of researchers who found a link between head ornamentation and theropod gigantism.

Terry Gates, a paleontologist who lectures at North Carolina State University, wondered if there was any relationship between cranial ornamentation, like bony crests, horns, and knobs, and rapid gains in size. Along with colleagues, Gates examined 111 theropods of various shapes and sizes, some of whom had skulls adorned with ornamentations while others lacked any headgear.

After they fed the data they gathered in a computer model, the researchers found that those theropods weighing under 36 kg (80 pounds) completely lacked any kind of cranial ornamentation. However, above this threshold, 20 of the largest 22 theropods employed a headdress.

What’s particularly interesting is that these theropods with head displays made large leaps in size over the course of their evolution, every 4 to 6 million years. On average, these dinosaurs evolved to giant sizes 20 times faster than those theropods who lacked cranial ornaments, such as Acrocanthosaurus.

“We were surprised to find such a strong relationship between ornaments and huge body size in theropods,” Gates explains. “Something about their world clearly favored bling and big bods.”

Gates says that this trend is significant and shouldn’t be ignored. Scientists generally agree that such ornamentations, either those of dinosaurs or those found in animals today like elk, serve to attract mates or fend off rivals. But could there be more to it?

To try to get to the bottom of things, Gates and colleagues are now studying Galliformes, which are birds like chicken, turkey or quail. These animals are the direct descendants of the lineage of dinosaurs which survived the mass extinction event that ended their rule some 65 million years ago.

Judging from fossils of VelociraptorOrnithomimus, and Falcarius, some of the direct descendants of birds, these theropods defy the observed pattern. These dinos lacked any kind of body head display, despite being heavier than 36 kg. Gates suggests that they didn’t need body head display, which can be costly from an evolutionary standpoint requiring reinforced vertebrae for instance, as long as they had feathers.

“The best explanation is that the long stiff feathers, which originated in this group of dinosaurs and were similar to modern bird feathers, could perform equally well as social signals when compared to the bony displays in T. rex or Dilophosaurus,” Gates surmises.

The findings appeared in the journal Nature Communications.

A detail of a thin section through the tooth of a large theropod, Gorgosaurus, from Alberta. Credit: Danielle Default

T-rex and other top dinosaur predators had serrated teeth to butcher their prey

A novel analysis reveals T-rex and other theropods – the top land predators that dominated the planet for no less than 165 million years – had teeth of unrivaled complexity. The long and powerful teeth were serrated like steak knives to disembowel prey easily, while on the inside tissue supported the teeth for maximum resistance against the powerful sheering stress which followed each bite.

Gorgosaurus feeding on a young Corythosaurus in Alberta, Canada, 75 million years ago. Image: Danielle Dufault

Gorgosaurus feeding on a young Corythosaurus in Alberta, Canada, 75 million years ago. Image: Danielle Dufault

Over millions of years, theropods developed an unrivaled arsenal. Though not very fast, these huge beasts would overwhelm any prey, no matter how large, which had the misfortune of encountering a theropod. Among the fossil teeth analyzed by University of Toronto Mississauga paleontologist Kirstin Brink and colleagues were those belonging to the smaller Coelophysis and bird-like Troodon, but also large predators Allosaurus, Gorgosaurus, Daspletosaurus, Tyrannosaurus and Carcharodontosaurus, along with those of semi-aquatic Spinosaurus.

“[..] The serrations were most efficient for piercing flesh and gripping it while ripping off a chunk of meat, called the ‘puncture and pull’ feeding style,” Brink said.

A detail of a thin section through the tooth of a large theropod, Gorgosaurus, from Alberta. Credit: Danielle Default

A detail of a thin section through the tooth of a large theropod, Gorgosaurus, from Alberta. Credit: Danielle Dufault

The researchers carefully section fossilized teeth, either alone or confined in the ribs and other bones of prey, then used a scanning electron microscope and a synchrotron. This offered an unprecedented view both of the meat eaters’ tooth structure and chemical composition. Like a very strong saw, the teeth of T-rex and its cousins were disposed in a manner that allowed each teeth to be supported by those surrounding it. When and if a tooth happened to come out, it would be replaced. T-rex, for instance, took two and a half years to grow a new tooth.

“It could take up to two years for a tooth to grow back in the big theropods like T. rex. Therefore, having specially reinforced teeth means less tooth breakage and less gaps in the jaw, leading to more efficient eating,” Brink said.

Today, only one animal with serrated teeth is still alive: the infamous Komodo dragon. The 10 foot long Indonesian lizard has teeth that closely resemble those of ancient theropods. It uses them to chomp  huge prey, life buffalo. Interestingly enough, the Komodo isn’t a descendant of dinosaurs and evolved its serrated dentures independently.

Artist impression ofthe Daemonosaurus chauliodus shows its size relative to an American quarter. (c) Jeffrey Martz

New dinosaur species found bridges evolutionary gap

Artist impression ofthe  Daemonosaurus chauliodus shows its size relative to an American quarter. (c) Jeffrey Martz

Artist impression ofthe Daemonosaurus chauliodus shows its size relative to an American quarter. (c) Jeffrey Martz

A team of paleontologists from the Smithsonian Institute have uncovered the fossils of a brand new dinosaur species in Ghost Ranch, New Mexico which posses a particular importance by filling the family tree gap between early predatory species such as Herrerasaurus and later theropod dinosaurs.

Researchers named the species Daemonosaurus chauliodus, based on the Greek words “daimon” meaning evil spirit, since it was found in Ghost Ranch (superstitious excavators, uh?) and “sauros” meaning lizard or reptile. The species name chauliodus is derived from the Greek word for “buck-toothed” and refers to the species’ big slanted front teeth as seen in the skull and neck of the Daemonosaurus, which were actually the only fossils found.

Because of the scarce number of fossils, it’s size is difficult to asses it’s length. What researchers know, though, is that the dinosaur’s skull is narrow and relatively deep, measuring 5.5 inches long from the tip of its snout to the back of the skull and has proportionately large eye socket.

Scientists have dated the Daemonosaurus approximately 205 million years ago, in the Triassic Period, just before the beginning of the Jurassic Period, which posses a remarkable significance since all basal (primitive) dinosaurs had vanished millions of years earlier.

“Various features of the skull and neck in Daemonosaurus indicate that it was intermediate between the earliest known predatory dinosaurs from South America and more advanced theropod dinosaurs,” said Hans Sues, curator of vertebrate paleontology at the Smithsonian’s National Museum of Natural History and lead author of the team’s findings. “One such feature is the presence of cavities on some of the neck vertebrae related to the structure of the respiratory system.”

This new discovery shows that there is still much to be learned about the early evolution of dinosaurs. “The continued exploration of even well-studied regions like the American Southwest will still yield remarkable new fossil finds,” Sues said.