Characteristics and Behaviors of Pterosaurs Overview Pterosaurs were not dinosaurs but were closely related, and existed for 150 million years beginning in the late Triassic period through the Jurassic and Cretaceous periods until eventually becoming extinct along with the rest of the earth’s population at what is now known as the KT boundary event. The KT boundary event was the mass extinction that occurred at some point in time between the Cretaceous (K) and the Tertiary (T). This is famous
is attached to the fourth trochanter (a diagnostic feature of the majority of archosaurs, which maniraptorans and birds lack completely). This form of locomotion is often characterised as “hip-driven” and is seen in today’s crocodiles, with the caudofemoralis longus, attached on the fourth trochanter, serving as an important locomotor muscle. This is likely to be the mechanism of locomotion that the primitive archosaurs used, since the majority of limbed reptiles locomote in a similar manner. In birds
Riley 6 recognizable evidence for animals was discovered in Oman, this discovery revealed small sea sponges that were alive approximately 635 million years ago.” -Oldest fossil evidence for animals found. Nearing 443 million years ago occurred the third largest extinction in Earth’s history the Ordovician-Silurian extinction, during this extraordinary event almost 85% of all sea life had been wiped out. Preceding this event a giant formation of ice was collecting in the southern hemisphere. It was
the origin of the turtle (Testudines) is very controversial, and has been the source of experimenting to try to prove whether it should be placed under anapsid-grade parareptiles, according to Bayesian analyses, or diapsids as sisters to living archosaurs. The use of experiments including molecular scaffolding, which is an experiment involving using the scaffold protein of the backbone to place the turtles in a certain taxa, is used to show where turtles should actually be placed. I find it very
The Debate Over Birds and Feathered Dinosaurs Because dinosaurs are animals that lived millions of years ago, we are entirely dependent on the fossils that they have left behind for any understanding that we hope to gain. As any paleontologist will tell you, fossil hunting is difficult. There are no certainties, no guarantees. A certain amount of luck is as valuable as any scientific knowledge. Every so often a discovery is made that attempts to shake up pre-conceived notions of how the
Evolution is a theory that gives origin to Earth’s living things. The theory of evolution is considered as one of the fundamental keystones of biology. Even though it is only considered a theory, in biology theories are supported by much experimental evidence and express ideas that are certain. Evolution accounts for life’s unity and diversity. The hypothesis of evolution was first introduced by Jean Baptiste Lamarck in 1809. Lamarck proposed how life changes over time. His principles included the
Hypotheses On the Origin of Birds Since the advent of the theory of evolution the origin of birds has been a thriving topic in science. Many ideas and hypotheses have been presented, but only two stand today: that birds are descendents of ancient thecodont stem reptiles, and that birds are the direct descendents of a group of dinosaurs known as the coelurosaurs. Both hypotheses pose many interesting and insightful ideas based on information obtained from the fossil record. There is not enough
2. A stromatolite is a fossil of blue green algae, or cyanobacteria. They date back up to 3.5 billion years ago, and made other life possible by transforming earth’s atmosphere to one much more suited for terrestrial life, by creating oxygen gas. 3. Archean life was extremely basic, essentially making it harder for anything to go wrong with it. Life first appeared in an incredibly hostile environment, todays earth is much more hospitable and abundant with all sorts of life. 4. The Paleozoic era
This assumption is also anchored on the fact that then Deinonychus’ preys, tenontosaurs, were way bigger and heavier. However, this theory has been questioned by several sources who base their arguments on the fact that modern-day archosaurs like crocodiles are solitary hunters since these modern species have their own internal conflicts especially because larger members try to dominate. The bite force of the Deinonychus was between 4,100 and 8,200 newtons and could bite through a bone
groups, as well as their seemingly horrible and incredible nature, have enhanced dinosaurs' regular appearance. Persistent public interest for the animals has resulted in major support for dinosaur science. Dinosaurs can be generally described as archosaurs with limbs held erect beneath the body. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic Period. Birds are considered as a subgroup of dinosaurs by many palaeontologists. Some birds survived the extinction
Tyrannosaurus Rex The name says it all. This group of huge carnivores ruled the land during the Cretaceous period. Short but deep jaws, long hind limbs (legs), beady eyes, a long muscular tail, and tiny forelimbs (arms) make up a tyrannosaur. The Tyrannosauridae included such similar animals as Albertosaurus, Gorgosaurus, Daspletosaurus, Tarbosaurus, and of course Tyrannosaurus Rex. A tremendous skeleton of Rex now stands guard in the Valley Life Sciences Building in Washington. Tyrannosaurs belong
There are four main groups of reptiles, known as Crocodilians, Squamates, Tuataras, and Turtles. Crocodilians consists of large reptiles which includes alligators, crocodiles, gharials, and caimans. Squamates are lizards, snakes, and worm-lizards. A worm-lizard is a subterranean burrowing reptile that resembles an earthworm, a legless lizard. Tuataras are a group of reptiles that are lizard-like in appearance but are different from squamates because their skull isn’t jointed. Turtles are the most