Essay Tetrapods

The author and his colleagues specifically chose to focus on 375 million year old rocks in their search for fossils because this was the time frame that provided fish that would be useful to study from. The 385 million year old rocks provided fish that look too similar to the ones we have now and the 365 million year old rocks have fossils that don’t resemble fish. The 375 million year old rocks, however, provide fossils that show the transition between fish and land living animals.

Adaptive radiation of different organisms have occurred throughout geological time through the filling of ecological niches. Organisms different from one another are capable of radiating greatly, as they evolve traits that allow them to thrive better in their environment. The Anolis lizards of the Caribbean islands are a great example of a single genus to have radiated not once, but multiple times through very similar mechanisms. Different populations of the Anolis phenotypically vary in their morphological traits to facilitate adaptation to particular niches. These phenotypic variations have evolved in convergence in more than one occasion, as recently discovered fossil specimens show similar patterns in morphology to modern Anolis.

Tiktaalik roseae, the creatures scientific name, was found in Arctic Canada and it lived around 375 million years ago. The Tiktaalik’s remains were found in Nunavut Territory in Canada and therefore scientists asked locals to propose a name for the species. According to, A Fish Out of Water, “The Elders Council of Nunavut suggested “Tiktaalik”. This word means “a large, shallow water fish”.” Fishapod is a nickname for the Tiktaalik because some scientists believe that it is a missing link between fish and tetrapods, the first animals to walk on land that were four-legged. “Fishapod fossils indicate that the creature was a mixture of animal types,” explains Greg Pardo, the author of A Fish Out of Water. The fishapod had similar parts to four-legged land animals, such as a skull, a neck and a large ribcage. This large

1. The author chose to focus on 375 million year old rock because the transition from fins to necks and limbs occurred then. The scientists knew that any time later than this and they would find lots of animals with limbs. But if they searched earlier than this time then there are only fish without necks. When the fish were evolving they evolved necks before they evolved limbs so this was a good sign in chronology. Sedimentary rocks are the best types of rocks for fossil due to their gradual pressure and low amounts of heat. Sedimentary rock is also found in lake beds and streams, where fish and aquatic wildlife are most likely to live.

gills sprouting small feather-like appendages. Although colloquially known as a ‘walking fish’, it is in fact

The fossil of Tiktaalik confirmed a major prediction of paleontology in that it showed characteristics of both aquatic animals, such as fish, and land animals, such as reptiles and amphibians. While it had fins and scales, it also had a flexible neck, a flat head, and complex bone structure in its fins that correspond with the structure of the legs of terrestrial animals. Thus, it demonstrates the evolutionary transition between aquatic and terrestrial life.

Toe pad morphology in frogs is very similar in all frogs, even between arboreal and terrestrial species. The Litoria caerulea, commonly referred to as the Australian green tree frog, is an arboreal species. Its toe pad morphology consists of a hexagonal array of flat-topped epithelial cells that have mucus-filled channels inbetween.15 The toe pads of fully grown frogs are often larger, and are subdivided into middle and outside regions by large grooves that also fill with mucus.15 Although the toe pad as a whole is soft and easily deformable, the epithelium itself is stiffer in feel. In one study of toe pad morphology, nine toes from each frog, four from the front and five from the back were studied via scanning electron microscopy (SEM) and

During the Cambrian Period there was an explosion of life forms. Most of these were in the water. Many animals with no backbones lived in the shallow seas. These animals were invertebrates.

During the Devonian period, most of the oceans were filled with stromatoporoids, brachiopods and corals. The Devonian period gave rises to some of the first tetrapods, amphibians, sharks, insects and boney fish. The first real land plants were also formed, giving rise to the first forest. The first plants were only about a foot tall and had no roots or leaves. By the late Devonian, plants had formed roots and leaves.

Mainly caused by beneficial mutations, that helped them survive in their current environment. Animals such as the Mesonychids had four powerful limbs, much like dogs or wolves. They also had small hooves at the end of each of their toes. Ambulocetus were similar with dense bones and a long robust tail. Later on in whales evolution their bone structure changes. For example Ambulocetus had squat legs that splayed outward from the body. Zygorhiza the most recent example had front flipper and a fluked tail. Without legs or toes. Much like whales today. This shows how natural selection changes a body to survive best in their

Scientists say reptiles evolved from amphibians 340 million years ago. The first reptile was an insect eater. Reptiles were more adaptable and able to

The frog’s posterior appendages are “designed” to allow for a great release of energy. This energy propels the frog forward in its movement and allows the frog to travel. Therefore, the structure of the frog’s posterior appendages is related to the leg’s function, which is the ability to hop and provide movement to the frog. The frog lacks ribs.

Matrotrophy is the alternative reproductive method to laying shelled eggs in reptiles. With this maternal strategy, females can supply their unborn offspring nutrients from their own bodies via a placenta for their entire gestation period rather than relying on egg nutrient stores and external incubation (Itonaga et al. 2012). Squamates are known to contain several species that give birth to live young, contrary to the usual shelled-egg method of most other reptilian taxa such as the Crocodilians and Tuataras. Matrotrophy in Squamates likely has many origins and probably did not evolve as a result of one environmental element alone (Albergotti and Guillette 2011). The amount of maternal provisioning is vastly different between viviparous and

The word dinosaur was invented in 1842 by Richard Owen. Dinosaur comes from the Greek word “deinos” and “sauros” which translates to fearfully great lizard (“Learn about Dinosaurs”). Dinosaurs are always named in Greek and usually named after their unique fossils, where they 're found, it’s size or a person. Before a dinosaur can be officially named it must be approved by the International Commission on Zoological Nomenclature. It’s difficult to figure out how dinosaurs sounded, mated, behaved, what color/pattern they were and which ones are male or female. Paleontologists have however been able to discover that dinosaurs hatch from eggs, their bones have growth rings which can help figure out their age and that the larger dinosaurs lived for roughly 100 years and smaller ones for less. All dinosaurs evolved from other reptiles during the Triassic period. Dinosaurs are either herbivores or carnivores and are divided into two major groups. Bird hipped, Ornithischian, or lizard hipped, Saurischa. In the Saurischa hipped dinosaurs the pubis bone is down and to the front but in Ornithischian hipped it is point down and towards the tail (“Zoom Dinosaur”). The next step was to examine how dinosaurs behaved and their characteristics.

Frogs, toads, caecilians, and salamanders are the members of the class Amphibian (amphi- meaning “on both sides” and bios- meaning “life”). These members always require water for reproduction. Most Amphibians undergo metamorphosis, which is a usually degenerative pathological change in the structure of a particular body tissue. And, in the case of Amphibians, it is the changing of a tadpole into