On my last post T-Rex (of course) brought up some questions concerning blood vessels and keratin on dinosaurs. What is keratin? It is fibrous strings of protein that make up hair, claws, horn coverings and even the outer layer of human skin, not to mention fingernails. Wikipedia's opening description is as follows: "Keratin (/ˈkɛrətɪn/) is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin." Keratin forms the very pointed part of a cat's claws or an antelope's horns or a bird's beak and claws or a dinosaur's claws and horns. In the case of frilled, horned dinosaurs (Triceratops) it forms an outer covering on the frill, the horns and the face of the skull. Like a bird's bill the keratin can be very colorful and also like a bird's bill, when blood flow is increased in that area, the bill will become flushed and highly colorful. Stegosaurus plates operate in the same manner. Being covered in keratin raises some other issues. For a long time it was believed that Stegosaurus back plates and Triceratops horns and frills were for defense, then it was believed that the fragility of the bony structure made this not likely. But now with the understanding that these structures were covered in keratin, which can be extremely strong and resilient, it could be that the back plates, frills and horns were not just for display but for defense as well. Keratin can form shapes beyond what the underlying bone structure indicates to some degree. The Utahraptor foot claw in the image is large, but add the keratin and you are going to add a few more inches to the claw to where it forms the puncturing point. We haven't found any "mummified" Triceratops or Stegosaurs yet, but it could be that Stegosaur plates were strongly reinforced with keratin and maybe even came to very sharp points at their apex. We can only speculate and look at examples of modern animals. Besides the keratin, it is also now understood that the type of bone in Stegosaur back plates and Ceratopsian frills and horns is a bone structure that is more "plasticized" and able to flow and change shape during the animals growth stages. Certain animals that were thought to be different families or species are now understood to be juveniles or even old adults of one species. As an example, a juvenile Triceratops frill has small triangular points along the edge of its frill and their horns bend almost completely backwards. By the time they are a full adult, the triangular points are absorbed and the horns project more forward. There will be slight variations for each individual as well. The Hornbill is a great example of a modern bird with a strange accouterment that, in fact, has multiple uses. The Hornbill's horn is used for display, nest building, attack/defense, preening and hunting prey. It is omnivorous and so eats plants as well as small animals. It's binocular vision is partially obscured by the large "horn" but it gives the bird a precise look at it's own "horn" thus making it east to precisely manipulate its head to use the horn as a tool. Quite an evolutionary feat for an animal of supposed inferior intellect compared to a human. Notice the size of the young adult Triceratops skull compared to the doorway. A very large animal. The red circles highlight indentations in the frill and skull where blood vessels used to be. Please zoom. The T-Rex tooth would be covered in enamel, thus being larger, but you can see on the Utahraptor claw, striations from blood vessels and growth origins for the keratin sheath that would have covered it to form the hard yet sharp and flexible covering. The Iguanodon spike would also have been covered with keratin, like any animal claw or human fingernail. Birds are a branch of dinosaurs and their habits and behaviors are looked at more often to try to understand what habits dinosaurs may have had. While there cannot always be a direct correlation, due to body shape, size and environment, some concepts and ideas can be used to extrapolate theories and help better understand how these extinct creatures interacted with each other and their environment. These are photos I took while on vacation in Colorado a few years ago. Dino Ridge is about a half hour or less out of downtown Denver. There is a small museum, gift shop and about a mile hike along an abandoned portion of highway. The hike highlights rock formations from the Jurassic to the Cretaceous. There are dino footprints and numerous dino bones still in the native rock along the hike. Great education and easy for even smaller kids. There is also a cool view of Red Rocks from the west side of the ridge along the hike path. Thanks for stopping by.