Tiktaalik has both fish and tetrapod traits. Scales, fins, and gills are fish traits, whereas a neck, ribs capable of supporting weight, a flat skull, dorsally positioned eyes, a fin skeleton, and ear notches are tetrapod characteristics (The University of Chicago, 2006).
In conclusion, Tiktaalik is tetrapod-like in that it had both fish and tetrapod traits.
Tiktaalik is anatomically similar to both prehistoric fish and the first tetrapods. At first look, it appears to have fish-like characteristics such as fins, scales, and gills. It does, however, have a number of distinguishing characteristics that set it apart from its fishy contemporaries and make it quite appealing to scientists. For example, unlike any known fish today, it had an extra bone in its lower jaw called a hyoid. This may have helped the animal control water flow through its mouth when fishing or feeding.
Also unique to Tiktaalik is the fact that it was covered in skin folds. These probably functioned as small flaps that could be blown by wind or water movements to reveal parts of the animal's body. This may have been useful for hunting or escaping danger if needed. The skin folds also seem to have had some kind of lubricating quality, since they were made up of fat cells that contained oil.
Last but not least, Tiktaalik had four fingers on each hand and three toes on each foot. These are typical of most living amphibians, including frogs and salamanders. However, unlike those animals, it had evolved into its final form by the time it came onto the scene. So, even though it was originally discovered in Canada, researchers can now say with confidence that it is indeed a true member of Tetrapodia (the group of organisms that includes humans and dinosaurs).
Its shoulders are not attached to its head, allowing it to have a functioning neck, which fish lack. It also possesses ribs, which were utilized to support the body and help in living and breathing on land by some of the early tetrapods. Tiktaalik had an internal skeleton including a backbone and joints capable of moving.
Furthermore, like modern fish, tiktaalik had fins for locomotion instead of legs. However, unlike modern fish, its fins were used instead of feet to walk upon the earth. The skin covering tiktaalik's body was smooth and likely felt like leather against which to push off from while swimming or walking.
Finally, although it lacked true teeth, tiktaalik had a beak-like structure called a rostrum at the front of its jaw. This may have been used in eating as well as sensing predators nearby.
Thus, tiktaalik shows that fish did not need to evolve into tetrapods to become terrestrial animals. They could have continued to swim in what would have been an underwater world had it not been for tiktaalik breaking the surface every now and then to take in air. This demonstrates that fish were not limited to freshwater environments as was previously believed and that they could live in saltwater too.
First, Tiktaalik is better understood as a transitional form rather than a missing link. Tiktaalik, like other fish, has fins with thin ray bones, scales, and gills. It did, however, have the robust wrist bones, neck, shoulders, and strong ribs of a four-legged vertebrate. This combination of features indicates that it was evolving toward becoming a terrestrial animal.
Second, Tiktaalik fits well within the pattern of evolution found in nature. Living organisms evolve through small changes over many generations. Sometimes these changes are so small that scientists can't tell them apart. Other times they lead to new species. So evolutionary change doesn't always involve a single big jump. It can also happen bit by bit over time.
Third, scientists have found similar evidence for transitionals before Tiktaalik. In fact, the fossil record shows that while four-legged animals are being replaced by ones with backbones, there are often several different species involved. The fact that Tiktaalik has been identified using both skeletal and anatomical features helps explain this diversity. A complete skeleton isn't needed to know how to classify Tiktaalik because we already know its anatomy from living relatives.
Tiktaalik represents an early stage in the transformation of a fish into a land mammal. However, it still had some characteristics of its marine ancestor.
It's half tetrapod and half fish. Tiktaalik fossils exhibit functioning wrists, elbows, and shoulders, but they also have fish fin rays (Daeschler et al., 2006). Tiktaalik possessed both lungs and gills, according to new research. The study that reported this finding was published in June 2014.
Tiktaalik had an inner ear, as well as a balance organ called a otolith that acted like a miniature gyroscope. The bones of the middle ear were still present, but did not appear to be used for hearing.
The discovery of Tiktaalik provides new evidence that rebates its status from "half fish, half land animal." It shows that merges between fish and land animals are much more common than once thought. This means that if you went back in time, there would be no clear-cut division between fish and land animals because many species evolved from other species through gradual changes. Instead, there is just one group of organisms called "vertebrates" that contain both fish and land animals within them. Vertebrates split into two groups: amphibians and reptiles. Fish remained part of this group throughout their evolution.
Amphibians are creatures with both fish and land animal features. They usually have fins at some point in their life but lose them later on when they grow legs.
Tiktaalik's remarkable combination of gills, scales, fins, and lungs, along with a flexible neck, robust ribcage, and crocodile-like head, positioned it halfway between fish and the earliest four-legged land creatures. This evolutionary mystery creature has fascinated scientists for over 150 years because its bones are preserved in rocks formed 300 million years ago during the Paleogene period.
The main structures that help tiktaalik move from water to land are its shoulders and hips. The shoulder blades are large, movable bones that extend down toward the tail when tiktaalik is swimming in search of food or fleeing danger. When it lands on shore, these bones would have collapsed against each other, forming a flat surface that would have served as an effective paddling platform while searching for insects or small animals to eat.
The second key structure that helped tiktaalik become terrestrial is its hip. The ball and socket joint of this animal's hip would have fused after it died, forming a solid piece that could not be moved even when trying to walk on stones. This may have been useful when tiktaalik needed to protect itself from predators by luring them away from its young.
Finally, the third key structure that helped tiktaalik survive the land-to-water transition is its chest cavity.