Missoula – The wildlife we see around us today can help scientists figure out what prehistoric animals might have been up to.
This edition of A Wilder View examines why looking into the claws of our wildlife helps define the past.
Pretty much every animal you see has claws or nails and wildlife use these as tools to greatly assist in their daily lives. Claws are important to understanding wildlife behavior because they are the part of their bodies that interact directly with their environment.
Cheetahs use their claws like cleats to gain traction when running after an animal. Some marsupials have claws that are only used as an incomplete embryo to climb into their mother’s pouch which is later shed and new claws are grown to aid in locomotion or digging.
The amazing abilities of claws start with just two different parts.
“One is the core which is the bony part, and the other is the keratin sheath, and then together they make up the entire structure of the claw,” explained Dr. Tracy Thompson, a lecturer at the University of California, Davis.
Keratin is the same thing that nails, hair, and feathers are made of.
Thompson focused on his Ph.D. searching for Functional conformationStudy the shape of structures to determine or understand their function.
“I think of it kind of like tools. If you go to the tool cabinet, you get your shovels and your picks and screwdrivers and all these tools and you can kind of guess or infer what each of those tools are used for from the shape.”
What Thompson did in his thesis was create a method so that we can look at claws and accurately describe what they are used for. Since we cannot watch the behavior of prehistoric animals, he must evaluate how modern animals used their claws and infer why they used them.
“It then allows us to have a framework by which to infer or understand fossil organisms that we can no longer observe,” Thompson said.
His research allows them to correctly classify known animals by 95%.
“Which means we can take a fossil organism now and bring it into this analysis and have 95 percent confidence that we correctly interpret what that fossil organism is doing,” Thompson noted.
This search can be very complex. In modern animals, we can easily see the claw sheath, that part that goes over the bone. But fossils usually don’t contain a sheath and just bones, which means Thompson must carefully piece together what the sheath would be like on a fossilized bone.
Thompson said, “Trying to take that structure and use it to explain what this does. This is apples to oranges. A claw with a sheath might look or look very different than a claw without a sheath.”
Thomson also had to tackle another critical issue in the biological field. Being researchers they often put wildlife into a category based on where they live or what they do in their environment.
“They would classify organisms as eating other things, living in trees, or running on the ground,” Thompson said.
But those classes aren’t functions, Thompson says, they’re really a way of life, “The cat and the hawk are both predators, but they grab their prey in very different ways when it comes to claw use.”
A bird of prey that grabs – let’s say a rabbit – wraps its entire foot and talons around the rabbit to grab it in the same way as a bird grabs a branch.
Thompson explained that “instead of a tree bird and a predatory bird, these two species should be in the same class because the claws are used in exactly the same way for grasping a branch or for a hare.” “Although there is often overlap between mammals and birds.”
Thompson found that there is more variety in the use of claws in birds mainly because they can fly.
“Because birds specialize in hind limb claws because they can fly, they can really hone them on a very specific, very targeted shape to do something very specific. Whereas mammals, you need to run and climb or sprint and catch prey.”
Thompson had to reinvent the way scientists classify species based on their claw function to make this work. It was all done with a specific goal in mind.
“My goal all along has been to provide a basis for people to use and apply to fossils,” Thompson said. “I’m a paleontologist at heart and I want to be able to understand what organisms did in the past.”
Thompson has researched this for years and hopes future researchers will build on this by using it as a basis.
Thompson concluded, “That’s really valuable to me. To be able to take something and contribute it to the body of knowledge, for humanity, that can be beneficial.”