| Name | Tiktaalik | Diet | Carnivorous |
| Name Meaning | From the native word for large freshwater fish | Length | 2–3 meters (6.5–10 feet) |
| Pronunciation | tik-TAH-lik | Weight | 100 kg (220 lbs) |
| Era | Paleozoic – Late Devonian | Location | Canada (North America) |
| Classification | Sarcopterygii, Tetrapodomorpha, & Stegocephali |
Tiktaalik Pictures
The Tiktaalik
When scientists discovered the first fossil of the Tiktaalik in Devonian-aged rocks back in 2004, the newly discovered fish made news instantly.
While it was technically a fish, it had several bizarre features that suggest it may have lived beyond the water.
In addition to having scales and gills like a regular fish, the Tiktaalik had air-breathing nostrils on top of its head.
It also had fins that looked like they were designed to support its body like that of modern four-legged animals.
All these features made the Tiktaalik a one-of-a-kind discovery.
The combination of features displayed makes it a vital evolutionary link between regular fish and their four-legged terrestrial descendants.
So far, scientists have found more than 60 Tiktaalik fossils.
In this article, we’ll provide an overview of Tiktaalik, providing some insights into the appearance, life, and origin of this extinct, close relative of the tetrapods.
Physical Characteristics
Tiktaalik was a large fish.
But it is more commonly described as a “fishapod” because it showed both fish-like and tetrapod attributes.
It had an elongated, almost serpentine body that reached lengths of up to 2.75 meters (9.02 feet).
The Tiktaalik’s skull was low and flat.
It looked more like the skull of a crocodile than that of a fish.
The top of the skull had a pair of indentations that may have housed respiratory openings (spiracles) that may have linked to primitive lungs.
Tiktaalik had a pair of pectoral fins and pelvic fins with bony rays similar to that of modern fish.
However, these fins were more robust, with sturdy interior bones capable of supporting the fish’s weight in shallow water or on land.
Tiktaalik also had well-developed rib bones, which would have provided additional support for its body and could potentially aid breathing while out of water.
There were at least 45 rib bones between the fish’s skull and its hip area.
Tiktaalik was one of the first animals with a defined neck-like structure.
Unlike typical fish that tends to have bony plates in the gill area to restrict lateral head movement, the neck was separate from the skull and supported by a pectoral girdle (shoulder bones).
This neck-like structure made it possible for the fish to turn its head independently from the rest of its body, an essential adaptation for life on land.
The entire body of this fish was covered by scales similar to that of lobe-finned fish like the Panderichthys.
The scales were rhombic (diamond shaped), with a rough texture.
They were broad, with each one overlapping over the other from front to back.
Habitat and Distribution
Tiktaalik lived in North America during the Late Devonian Period.
Fossils of this fish have been found in rocks dating back to about 375 million years ago.
It inhabited freshwater environments, particularly in parts of present-day Canada.
The geographic range of this fish may have been limited to the northern region of the country, specifically in the Canadian Arctic.
Tiktaalik lived in shallow coastal areas and ancient waterways in this region.
The fish’s preferred habitat was slow-moving or stagnant freshwater, such as shallow seas, streams, and swampy areas.
The Tiktaalik’s ability to support its weight on this find and the fact that it had longs suggests that it could survive in terrestrial environments at least for short periods.
During the Late Devonian Period, North America was part of the supercontinent of Laurasia and located closer to the equator than its current position.
The climate in this region was generally warm and humid as compared to present-day polar conditions.
The level of carbon dioxide in the atmosphere was quite high, creating a greenhouse effect that raised global temperature.
The sea level during this period was also very high.
This created extensive shallow marine environments and vast inland aquatic habitats that were suitable for the Tiktaalik and other similar animals to thrive.
Behavior and Diet
Despite having tetrapod-like attributes, Tiktaalik mainly moved with a fish-like swimming motion.
The streamlined body and well-developed fins of this fish made it a proficient swimmer.
It was capable of propelling its body through the water using undulating motions of its body and paddling with its fins like modern fish species.
The Tiktaalik did have robust fins supported by wrist-like bones that may have allowed the fish to support its weight and “walk” along the bottom of shallow aquatic environments.
It is also likely that this fish was capable of venturing out of the water onto land for brief periods.
Scientists have found a strongly-built pelvic girdle for this fish.
This further supports the idea that it could prop up its body in shallow water or on mudflats.
Tiktaalik had a well-developed jaw and rows of sharp teeth effective for grasping prey.
The fish’s flat skull looked a lot like that of a crocodile.
Tiktaalik probably thrived on a diet of small aquatic prey.
Its elongated body, fin structure, and position of the fish’s eyes suggest that it was well-adapted to ambush hunting.
This involved lying in wait for unsuspecting prey to swim nearby before attacking quickly and grasping them with its strong jaws.
Since it lived in shallow water environments, Tiktaalik’s prey would have included smaller fish, invertebrates, and other aquatic organisms that inhabited these ecosystems.
The robust, limb-like fins of this fish were probably very instrumental for catching prey in shallow waters or even on land.
By propping itself up on these fins, Tiktaalik could have lunged forward to capture prey swiftly.
Life Cycle
Like modern fish and early tetrapods, Tiktaalik was most likely an egg-laying organism.
Reproduction and fertilization for this fish were most likely external, with the female releasing its eggs into the water while the male released sperm to fertilize them.
The eggs were laid in suitable aquatic environments, most likely shallow freshwater habitats.
The exact lifecycle and growth of this fish aren’t well-known from the fossil record but may have been similar to that of the amphibians, involving multiple stages of development.
New hatchlings were most likely in larval forms, with body structures slightly different from that of adults.
As they grew, they would undergo different stages of growth or metamorphosis, gradually developing more adult-like traits.
Growth in this fish may have also involved transitioning from a fully-aquatic lifestyle to more terrestrial habits.
Evolution and History
Tiktaalik is more popular for its tetrapod-like features, but it is actually a type of lobe-finned fish, a group known as the sarcopterygians.
It evolved approximately 375 million years ago during the Late Devonian Period.
This period was characterized by significant changes in Earth’s evolutionary landscape, especially as it relates to the planet’s vertebrate life forms.
Tiktaalik represents an intermediate stage in the evolutionary shift from fully aquatic fish to early tetrapods capable of supporting their weight on land.
This fish is considered a transitional form between non-tetrapod vertebrates such as Panderichthys and the early fully terrestrial tetrapods such as the Acanthostega and Ichthyostega, which were alive about 365 million years ago.
Although the Tiktaalik retained many of its fish-like features, it also developed several vital adaptations that foreshadowed the emergence of tetrapods.
Some of the most important adaptations include its limb-like fins, a neck allowing head mobility, robust ribs, and lungs that would have allowed breathing out of water.
The position of this fish as a transitional species would have also affected its behavior and ecological position in its ecosystem.
Tiktaalik lived a semi-aquatic lifestyle, which means it would have been capable of exploiting a wide range of habitats and resources that were inaccessible to fully aquatic fish species.
Interactions With Other Species
Tiktaalik lived in a shallow marine ecosystem which would have played a significant role in the types of prey and predator species it interacted with.
While it was not the biggest fish alive during the Devonian, it was one of the few species adapted to an oxygen-poor shallow marine environment.
This means it was probably the top predator in its ecosystem.
The Late Devonian Period was characterized by deciduous plants growing at the edge of the water bodies.
These plants shed their leaves annually into the water, providing nutrients and attracting small fish and other aquatic organisms into the shallows where this fish lived.
Tiktaalik was an opportunistic predator that hunted small fish, invertebrates, and possibly amphibians that lived in these shallow-water habitats.
The fish’s ability to prop itself on its fins would have made it easier to ambush its prey effectively, lying in wait for passing organisms before lunging forward to catch them.
Tiktaalik itself was probably prey for larger predators in its ecosystems.
This may have included larger fish, amphibians, and other large known and unknown predators that were part of the Late Devonian food chain when it was alive.
Cultural Significance
The Tiktaalik is often described as one of the best examples of a “missing link” in the fossil record.
The discovery of transitional fossils like this has helped scientists trace the evolutionary journey of aquatic animals as they gradually transformed into tetrapods.
The idea that land animals evolved from aquatic organisms has been known as far back as the 19th century.
But the absence of some vital fossil forms to demonstrate this transition left a gap in the fossil record that creationists often cite as evidence against the popular Darwinian evolution.
With the discovery of the Tiktaalik, scientists now had vital evidence to explain how vertebrates were able to invade the terrestrial ecosystem about 375 million years ago.
This does not mean that it is the direct ancestor of any of the terrestrial species alive today.
Several other related genera were making the transition from water to land around the same time, but Tiktaalik was one of the few marvelously preserved in the fossil record.
Studying missing links like this has helped to shed some light on the origin of limbs, lungs, and other adaptations that made the evolution of terrestrial life on Earth possible.
The discovery of this walking fish garnered widespread media attention and helped to increase public awareness regarding the concept of evolution.
After its discovery was announced, it became a sensational internet meme.
The memes humorously criticized the Tiktaalik for making the transition from sea to land and kickstarting the chain of events that would eventually lead to all present-day human suffering.
Conclusion
Tiktaalik is a genus of lobe-finned fish that was alive during the Late Devonian Period, about 375 million years ago.
Commonly described as a fishapod, this fish shows features similar to that of four-legged animals.
It was discovered in the Arctic region of Canada in present-day North America.
Tiktaalik had a flattened head with jaws adapted to a predatory diet.
But its most distinctive features were the robust fins that had sturdy interior bones, which may have supported the fish’s body similar to the legs of tetrapods that evolved after it.
Tiktaalik also had lungs and well-developed ribs, all features of an animal adapted to terrestrial life.
This mix of characteristics makes the Tiktaalik a crucial transition fossil whose discovery has provided valuable insights into one of the most vital stages of the evolution of life on Earth.
FAQs
Where was Tiktaalik discovered?
Tiktaalik fossils were discovered in 2004 on Ellesmere Island in Nunavut, Canada, within the Canadian Arctic region.
What other animals lived alongside Tiktaalik during the Late Devonian Period?
During the Late Devonian, Tiktaalik shared its environment with diverse organisms, including other fish species, early tetrapods, amphibians, invertebrates, and various marine life forms.
What does the name “Tiktaalik” mean?
The name “Tiktaalik” is derived from the Inuktitut language of the Inuit people of the Canadian Arctic.
It means “large, freshwater fish,” reflecting its discovery location and ecological context.
Sources
- https://evolution.berkeley.edu/evo-news/what-has-the-head-of-a-crocodile-and-the-gills-of-a-fish/
- https://www.smithsonianmag.com/science-nature/evolution-animal-intelligence-begin-tiktaalik-180951428/
- https://en.wikipedia.org/wiki/Tiktaalik
- https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/t/Tiktaalik.htm
- https://www.britannica.com/animal/Tiktaalik-roseae
- https://www.theguardian.com/science/2014/jan/13/tiktaalik-fossil-fish-four-legged-land-animal
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