Dinosaurs have always wielded claws, from the earliest now-extinct species to today's birds, but a new study has determined that dino claw types changed a lot as these animals evolved into modern birds.
"Other skeletal features changed as well, either as a response to a different diet or to optimize flight," the study's author, Stephan Lautenschlager, told Discovery News.
Lautenschlager, a vertebrate paleontologist at the University of Bristol, added that the first dinosaur claws "were recurved and short." As dinosaurs evolved during the Triassic, claw types began to vary. In this image from the book "Dinosaur" by Steve Brusatte, a herd of primitive carnivorous dinosaurs is enveloped by a sandstorm while a large crocodile-like animals and dinosaurs lurk in the background. Lautenschlager notes that the carnivores had claws that were "used to grasp and hold down prey." Some herbivore claws looked more like hooves.
Eoraptor was an early dinosaur that lived around 231 million years ago. It had five digits on each of its forelimbs, with three of these ending in large claws ready to grasp any and all edibles. It's little wonder that Eoraptor was an omnivore.
One of the largest meat-eating dinosaurs from the Triassic was Gojirasaurus, which grew to over 18 feet long. Smaller animals from what is now New Mexico, where "Godzilla Lizard" lived, were probably goners once this skilled hunter sunk its claws and teeth into their bodies.
Triassic dinosaur Tawa hallae was yet another carnivore that once terrorized what is now New Mexico. Its digits might have been thin and spindly, but they were guarded by an armor-like covering and tipped with sharp claws.
This dinosaur's lineage did not eventually evolve into birds, and it certainly doesn't look like any of today's birds, but there are commonalities. For example, paleontologist Sterling Nesbitt of the University of Texas at Austin said, "All dinosaurs share a common feature, an open hip socket, and you can dissect your Thanksgiving turkey and still see that original feature."
Sauropodomorph dinosaurs, such as Glacialisaurus hammeri from Antarctica, were the largest animals to ever walk the earth. Glacialisaurus lived during the Early Jurassic 190 million years ago. While it only ate plants, this 6-ton beast could use its incredibly sturdy claws to hoist its body up the lower level of trees. Antarctica then was more verdant, supporting a vast array of plants and animals.
Some dinosaurs appear to have been caring parents. Eggs for the dinosaur Citipati were found within a nest unearthed at what is now the Gobi desert of Mongolia. In this case, claws take on a more parental, gentle function. They drape around eggs, helping to protect them and hold them in place. Given the number of eggs, researchers suspect multiple females contributed to laying them, and males might have guarded them. The dino on top of the eggs in the image, therefore, might be a proud dino dad.
The Cretaceous was a time of tremendous change for non-avian dinosaurs. Some went on the evolutionary path to birds, while others went the proverbial way of the dinosaurs and became extinct. Talos sampsoni, a raptor, was in the former group. This feathered dinosaur was closely related to birds.
Lindsay Zanno, a Field Museum of Natural History researcher who studied the dino, said it took a licking but kept on ticking. Damage to its sharp talon suggests "that these animals regularly put this toe in harm's way," Zanno said.
T. rex, as its name suggests, was the king of the dinosaurs. This Cretaceous giant, which grew up to 40 feet long, could chomp down on prey with around 3,000 pounds of biting force. Its three hind limb claws were sharp and ready for hunting action. T. rex definitely did not strangle other animals with its forelimbs, though. They were super short, with tiny claws to match. It's still a mystery as to how they were used.
Therizinosaurus lived close to the time of T. rex, but it was a peaceful herbivore. While T. rex was known for its ravenous quest for meat, the claim to dino fame for Therizinosaurus was its huge claws, which were the longest known from any animal. The claws measured around 3.3 feet in length.
"In therizinosaurs, different claw shapes evolved, which deviate considerably from those of carnivorous dinosaurs," Lautenschlager said. "According to the recent study, large recurved claws appear to have been adapted for digging, whereas the straight and elongate claws were used to 'rake' vegetation."
Dinosaur claw shapes therefore became even more varied during the non-avian dinosaur evolution to birds. To this day, birds have many different types of claws, suited for particular uses and environments. Some forms are better for grasping perches and prey, as for raptors. Others are better suited to additional tasks, such as climbing, scratching and flesh-piercing kicks.