How did lobe-finned fish evolve?

The lobe-finned fishes diverged from the ray-finned fishes about 450 million years ago (mya) and were highly successful during the Devonian, when hundreds of species lived in the oceans and rivers of most continents.

What is the evolutionary significance of lobe-finned fish?

The fins are very flexible and potentially useful for supporting the body on land, as in lungfish and tetrapods (vertebrates with four limbs). Tetrapods are thoughto to have evolved from primitive lobe-finned fish.

What key changes took place in the evolution of fish jaws?

Major morphological changes occurred to the structure of elements of the jaw support skeleton, including variations in patterning and loss of the opercular series and symplectic. Over time, the hyomandibula became reduced and dissociated from the jaw in fish to become the stapes of the ear in reptiles.

What class is the lobe-finned fish an ancestor of?

class Sarcopterygii
Lungfishes, which are taken by many to resemble the earliest ancestor of tetrapods, are members of the class Sarcopterygii (lobe-finned fishes) and the subclass Dipnoi.

What is the evolutionary origin of fish?

The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish.

How did fish evolve into land animals?

In the Middle Devonian, roughly 385 million years ago, the first vertebrates began making their way out of water. For these pioneering fish, the adaptation of fins into limbs facilitated the transition.

When did lobe-finned fish first appear?

The first lobe-finned fishes, found in the uppermost Silurian (ca 418 Ma), closely resembled spiny sharks, which became extinct at the end of the Paleozoic. In the early–middle Devonian (416 – 385 Ma), while the predatory placoderms dominated the seas, some lobe-finned fishes came into freshwater habitats.

What were the first vertebrates to evolve?

The earliest vertebrates were jawless fish, similar to living hagfish. They lived between 500 and 600 million years ago. They had a cranium but no vertebral column. The phylogenetic tree in Figure below gives an overview of vertebrate evolution.

How did fish jaws evolve?

The jaw evolved from repeating pharyngeal segments first present in chordate ancestors as respiratory structures, later giving rise to cartilaginous branchial baskets of jawless fishes and the bones and cartilages of the facial, upper and lower jaw, jaw support, and posterior gill or throat structures (viscero- or …

Which structures did jaws evolve from?

Jaws probably originated in the pharyngeal arches supporting the gills of jawless fish. The earliest jaws appeared in now extinct placoderms and spiny sharks during the Silurian, about 430 million years ago.

What was the first lobe-finned fish?

The earliest fossils of sarcopterygians were found in the uppermost Silurian, about 418 Ma (million years ago). They closely resembled the acanthodians (the “spiny fish”, a taxon that became extinct at the end of the Paleozoic).

How has a fish changed over time?

The earliest fish, resembling living hagfish, evolved about 550 million years ago. Adaptations that eventually evolved in fish include a complete vertebral column, jaws, and an endoskeleton made of bones instead of cartilage. Fish live throughout the ocean and in freshwater lakes and streams.