Essay Tetrapods

A dinosaur has an antorbital fenestra with an open hole hip socket. The definition differs from the term used informally because it helped understand how the dinosaur moved and how they were categorized as species. There are four general characteristics that dinosaurs have as a result of their synapomorphies which are permeated acetabulum, ball-shaped head on proximal femur, the Cnemial crest on the proximial tibia, and an ascending process on astragalus. These four dinosaur synapomorphies are related to vertical limb support.

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.

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.

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

Vertebrates are known to be animals with backbones. Tooth reduction is one of the major evolutionary trends that developed among major vertebrate groups that allowed for the transition from aquatic to terrestrial life. Evolution of limbs and being able to breath air are other evolutionary trends that took placeThese trends include improved respiration and protective and insulating body coverings. More over the transition from water to land also included changing to more efficient reproductive methods like having a placenta for some animals or egg layers for other animals. Lastly, the morphology of organisms evolved such that for land they would have paired, muscular appendages used for crawling 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.

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

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

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

On this image, we see the external dorsal side of a preserved crayfish. As part of the largest animal phylum the Arthropoda, the body of the crayfish is segmented, with jointed appendages and exoskeleton. The paired antennae (1) are long appendages located the front of the mouth and modified for help the animal to sense touch and taste. The antennules (2) are shorter, also paired with the same function but they also help to maintain balance. The chelipeds (3) are located on the front of the thorax, and they are responsible for defence and grasping food. On the at ventral part of the thorax, we found four pairs of walking legs (4), with these legs the crayfish changes locations on the bottom of freshwater lakes, streams and also on land. They

Fossils provide a record of how organisms have evolved overtime, as they contain the remains of life trapped in sediment, ice or amber and preserved for over millions of years. Transitional fossils, which provide evidence for evolutionary change, have features that show the transition of characteristics of organisms from ancestors to descendents. An example is Archaeopteryx, which featured reptilian features, including teeth and skeleton, however, also had feathers and a wishbone sternum (used to attach muscles for flying). The evidence of the fossil shows the evolutionary transition between dinosaurs and

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

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