Dinosaur Sighting: Star-Spangled Theropod

A patriotic theropod in the vicinity of Beloit, Wisconsin. Photo submitted by David Rice.

Today’s Dinosaur Sighting comes to us from David Rice, who spotted this star-spangled theropod dinosaur in the vicinity of Beloit, Wisconsin. As David pointed out in his e-mail, the top half of the dinosaur is reminiscent of a tyrannosaur, but the feet have weird lumps which look like the sickle claws of the “raptors;” maybe it is some kind of hybrid. Whatever the theropod is meant to be, though, it is hardly the only patriotic dinosaur around—in previous posts we’ve featured a Stegosaurus covered in stars and stripes and “George Washasaurus.”

Have you stumbled across a dinosaur in an unexpected place? If you have, and have a photo of the encounter, send it to us via dinosaursightings@gmail.com!

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The Existence of Dinosaurs

Dinosaurs were recorded to be fierce and huge creatures of the past. They are considered as reptiles and feed mainly on meat and plants. Many people around the world are fascinated by these creatures. These have been featured in several movies already, like the Jurassic Park.

The word dinosaur was derived from the Greek words deinos and sauros which together means terrible lizard. Dinosaurs are prehistoric animals that have existed over 200 million years ago during the Mesozoic Era. These creatures have grown in many different kinds during their existence on earth and have disappeared mysteriously during the Cretaceous Period. Based on study, there are 700 types of dinosaurs which were identified but it is believed that there are more which have not yet been discovered.

Researchers continue to look for fossils to find answers to the existence of these prehistoric creatures. Fossils have been found in almost all the continents in the world. Most are found in Asia and North America.

Dinosaurs vary greatly in size. The smallest among the dinosaurs is the Compsognathus, similar to the size with a hen only. Among the largest is the Sauropod which measures at about 100 feet in length. This type of dinosaur features a long neck known as a plant eater.

Basically, dinosaurs are classified according to its size and shape. Dinosaurs who feed from meet (carnivorous) are called Theropods. These are considered as bipedal animals with 3 toed feet. The Carnosaurs belong to the Theropod family which is small and is also the fastest among its kind.

Among the larger kind are the Sauropods, a four legged dinosaur like the Apatosaurus, Brachiosaurus and the Diplodocus. The Ankylosaurs are dinosaurs which feature spiny tails with strong armored bodies. There are also dinosaurs which have horns on top of their head like the Triceratops and are classified as Ceratopians.

There are other existing animals during the Mesozoic Era that many people mistakenly identify as dinosaurs. These creatures are actually not because they don't have the same traits as the dinosaurs. Researchers have identified traits of dinosaurs.

In general however, dinosaurs bear some basic traits. Dinosaurs are four legged animals but some of their kind walks on two legs. They basically dwell in land. Their bone and muscle structures are unique. They have cheek muscles which extends from the jaw connected to the skulls.

Dinosaurs have a vertical gait and usually extend their bodies above their legs. Their hip girdles are composed of three bones namely pubis, ilium and ischimum.

Researchers rely so much on fossils to study and recreate how dinosaurs look like during their period of existence. Study shows that some dinosaurs have sharp and pointed teeth while others have flat teeth. This means that those who have sharp teeth eat meat while those with flat teeth feed mainly on plants.

Scientists also proved that dinosaurs can run fast due to its well proportioned leg bones. They also discovered that dinosaurs have a sensitive sense of hearing and site based on the cavities that were found in their skull.

Since dinosaurs are associated to be of close relationship with birds and reptiles, scientist assumes that dinosaurs lay eggs. This has been proven when researchers were able to discover a fossilized egg in many different locations of the world.

However, scientist still has to study to learn more on the rituals of these creatures when mating. But one thing is proven, that dinosaurs can easily reproduce based on its domination of the whole land area for a hundred million years.

For more information on Jurassic Dinosaurs and Mesozoic Dinosaurs, please visit our website.

The Making of a Tyrant

The reconstructed skeleton of the Tyrannosaurus rex specimen known as "Black Beauty". From Wikimedia Commons.

Tyrannosaurus rex was an obligatory inclusion in every book and documentary about dinosaurs I saw as a kid. It was the tyrant king of all dinosaurs, the supreme predator of the end-Cretaceous, but for all its majesty no one could explain where it had come from. Along with its kin—such as Albertosaurus and Tarbosaurus—Tyrannosaurus simply seemed to be the culmination of a trend towards larger size and ferocity among predatory dinosaurs, but plotting the succession of giant theropods during the course of the Mesozoic did not seem to provide many clues about the origins of the tyrannosaurs.

As summarized in a new Science review by a team of tyrannosaur experts, however, new discoveries made in the last decade have finally placed Tyrannosaurus in its proper evolutionary context. In the past year alone, no less than six new tyrannosauroids have been either discovered or identified from previously-known specimens, and this growing knowledge of tyrannosaur evolution has confirmed that the largest predators of Late Cretaceous North America started off small. The first tyrannosaurs were not derived from already-large Jurassic predators such as Allosaurus, but instead were relatively small coelurosaurs, with small heads and long arms, which evolved during the Middle Jurassic more than 165 million years ago. Proceratosaurus, a crested dinosaur from England once believed to be closely related to Ceratosaurus and other early theropods, was just recently found to be one of the first tyrannosauroids. At a glance, Proceratosaurus and similar tyrannosaurs would have looked more like “raptors” than like their more famous relatives. Exceptionally-preserved specimens of the Early Cretaceous tyrannosauroid Dilong from China show that, like their relatives among the coelurosauria, these dinosaurs were covered in feathery dino-fuzz.

After almost a century of uncertainty, it was finally confirmed that enormous Late Cretaceous tyrannosaurs evolved from small, elaborately-ornamented coelurosaurian ancestors. The approximately 80 million years between the first tyrannosaurs and the radiation of truly giant forms is still relatively sparsely known, though. The recent discovery of the long-snouted genus Xiongguanlong and the announcement of the miniature tyrant Raptorex have illustrated that there was no single, slow evolutionary march towards the Tyrannosaurus rex body form. Instead there was a radiation of relatively small genera which preceded the development of large body size, and there are probably a number of strange Late Jurassic and Early Cretaceous tyrannosaurs waiting to be found.

There is more to recent tyrannosaur research than just filling out evolutionary trees, though. Not only is Tyrannosaurus rex the most famous of all dinosaurs, but thanks to numerous specimens and decades of scientific study it is also the most extensively studied. Bite forces, brain anatomy, running speed, growth rates, bone microanatomy, biogeography and other aspects of its paleobiology have all been—and continue to be—extensively investigated. The abundant remains of some of its close relatives, such as Albertosaurus, have even allowed paleontologists to see how different the last tyrannosaurs were; paleontologists could hardly wish for better fossilized records of these dinosaurs. Research will continue, and new discoveries will continue to revise our understanding of tyrannosaur evolution, but it is wonderful that a more complete history of the tyrannosaurs is beginning to come together.

References:

Brusatte SL, Norell MA, Carr TD, Erickson GM, Hutchinson JR, Balanoff AM, Bever GS, Choiniere JN, Makovicky PJ, & Xu X (2010). Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms. Science (New York, N.Y.), 329 (5998), 1481-1485 PMID: 20847260

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