Tiktaalik roseae
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What is Tiktaalik roseae?
Tiktaalik roseae is an extinct fishlike aquatic animal that lived roughly 380–385 million years ago during the late Devonian Period. Its genus name comes from the Inuit language of eastern Canada and means "large freshwater fish living in the shallows." The species name roseae recognizes a benefactor of the 2004 fossil discovery in northern Canada.
T. roseae is one of several fossil forms that have improved scientific knowledge of the transition from aquatic vertebrates to land vertebrates. Tiktaalik had scales on its dorsal area and retained bony fin rays. It had a broad, flat skull with eye sockets facing upward, a long crocodile-like body, and limbs that were between fins and legs.
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When and where was Tiktaalik roseae discovered?
Tiktaalik roseae, a close relative of the direct ancestors of tetrapods (four-legged land vertebrates), lived roughly 380–385 million years ago during the late Devonian Period. The fossils, consisting of a few nearly complete skeletons and several dozen partial specimens, were discovered in 2004 on southern Ellesmere Island, Nunavut, northern Canada. The genus name Tiktaalik comes from the Inuktitut language of the Inuit people of eastern Canada and is a general term for a large freshwater fish that lives in the shallows. The species name, roseae, honors a benefactor of the research. Learn more about Tiktaalik roseae.
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Why is Tiktaalik roseae important in the study of evolution?
Tiktaalik roseae, from about 380–385 million years ago, is vital to the study of evolution because it is a close relative of the direct ancestors of tetrapods (four-legged land vertebrates). T. roseae is one of a series of fossil forms discovered since the 1960s that have greatly improved scientific knowledge of the emergence of vertebrates onto land. The aquatic Eusthenopteron and the (at least partly) terrestrial Ichthyostega are now understood to be bridged by forms such as Panderichthys, Elpistostege, and Acanthostega as well as Tiktaalik.
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What features make Tiktaalik roseae similar to both fish and land animals?
Tiktaalik roseae, from about 380–385 million years ago, is a key fossil showing the emergence of vertebrates onto land. It had a broad, flat skull with eye sockets facing upwards and a crocodile-like body. Its limbs were between fins and legs, with a pattern that may be the start of bones that became forearm and hand bones in tetrapods. The structure of its limb joints and enlarged ribs suggest it could clamber in shallow water and maybe on land, though its skeleton wasn't broadly suited for land. It also retained the ability to swim, with fin rays and a streamlined body. Its snout and lack of gill covers suggest it snapped up prey.
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How did Tiktaalik roseae help scientists understand the transition from water to land?
Tiktaalik roseae, an extinct aquatic animal from approximately 380–385 million years ago, is a crucial fossil in understanding the water-to-land transition of vertebrates. The discovery of T. roseae, along with other fossils, has enhanced the scientific understanding of the evolutionary steps between aquatic vertebrates and the first land vertebrates.
Tiktaalik had a broad, flat skull with eye sockets facing upward, a crocodile-like body, and limbs that were intermediate between fins and legs. Its limb joints and enlarged ribs suggest it could use its front and rear limbs to move along the bottoms of watercourses and perhaps even on land. Though it retained the ability to swim, its features suggest the emergence of vertebrates onto land.
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What does the discovery of Tiktaalik roseae tell us about the evolution of vertebrate limbs?
The discovery of Tiktaalik roseae, which lived roughly 380–385 million years ago, has enhanced the scientific understanding of how aquatic vertebrates transitioned to land vertebrates. Tiktaalik had features of both fish and tetrapods (four-legged land animals). Its forelimbs, for instance, display a pattern of a central limb axis that divides at each new joint into two bones. The branching pattern is suggestive of the beginnings of bones that would become the forearm and hand bones of tetrapods. The structure of its limb joints and enlarged ribs show it could flex enough to move around, using its front and rear limbs to push its body along the bottoms of watercourses.
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Tiktaalik roseae, an extinct fishlike aquatic animal that lived about 380–385 million years ago (during the earliest late Devonian Period) and was a very close relative of the direct ancestors of tetrapods (four-legged land vertebrates). The genus name, Tiktaalik, comes from the Inuktitut language of the Inuit people of eastern Canada and is a general term for a large freshwater fish that lives in the shallows. The species name, roseae, honours a benefactor of the research that led to the finding of the fossils in 2004 on southern Ellesmere Island, Nunavut, northern Canada. The fossil find consisted of a few nearly complete skeletons and several dozen partial specimens.
T. roseae is one of a series of fossil forms discovered since the 1960s that have greatly improved scientific knowledge of the transition between aquatic vertebrates and the first land vertebrates. The aquatic Eusthenopteron and the (at least partly) terrestrial Ichthyostega, both of late Devonian age, are now understood to be bridged by forms such as Panderichthys, Elpistostege, and Acanthostega as well as Tiktaalik. However, it is inaccurate to claim that Tiktaalik and the other forms represent some sort of “fish-amphibian transition” or are a “missing link” between fishes and amphibians. Tiktaalik and the other animals looked nothing like conventional ray-finned fishes such as trout and were not closely related to them; likewise, the first tetrapods on land were nothing like familiar amphibians of today such as frogs and salamanders. Tiktaalik and the other forms were actually akin in many respects to the ancient lungfish and coelacanth species that survive to this day. For this reason, they are better described as representing the “emergence of vertebrates onto land.”
T. roseae had nearly square, narrowly overlapping scales on its dorsal area, and it retained primitive features such as bony fin rays, which are lost in animals that mainly walk on land. In general form, it had a broad, flat skull with dorsally facing eye sockets, a long crocodile-like body (some specimens reach almost 3 metres, or 10 feet, in length), and limbs that were intermediate in many respects between fins and legs. The forelimbs, for example, show a common pattern of a central limb axis bifurcating at each new joint into two bones, the anterior one being smaller and generally unbranched and the posterior one being robust and branched. However, in Tiktaalik there was more branching on both axes, and it is tempting to see in this pattern the beginnings of bones that eventually would become some of the forearm and hand bones of tetrapods. The hind limbs were supported by a primitive but robust pelvic girdle. The structure of the limb joints and the enlarged ribs of Tiktaalik show that the animal could flex enough to clamber about, its front and rear limbs pushing the body along the bottoms of watercourses, at least in the shallows, and perhaps a bit on land, although its skeleton was not otherwise broadly adapted for that purpose. The fin rays covering the ends of its limbs and its flattened, streamlined body plan indicate that Tiktaalik retained the ability to swim. Its long snout and lack of gill covers suggest that it snapped up prey, rather than inhaling it as fishes do.
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