Lobe-finned fish (Sarcopterygii)

The Sarcopterygii, or lobe-finned fishes, is a clade containing the coelacanths, lungfishes, tetrapods, and their fossil relatives, including the osteolepiformes and panderichthyids. They are the sister group to the ray-finned fishes (Actinopterygii), together forming the bony fishes (Osteichthyes).
Sarcopterygians are characterised by their fleshy pectoral and pelvic (paired) fins that articulate with the pectoral (shoulder) and pelvic (hip) girdles via a single bone. This is apparent in the coelacanths and lungfishes, which are more intuitively fish-like. These lobe-fins gave rise to the paired limbs of tetrapods, with the single bones representing the humerus (forelimb) and femur (hindlimb).
The oldest sarcopterygians were found in the Uppermost Silurian. The first Sarcopterygian closely resembled Acanthodians. The sarcopterygians closest relatives at the time were the actinopterygians (ray-finned fishes). Sarcopterygians probably evolved in the oceans, but they later came into freshwater habitats, possibly as an adaptation to avoid the predatory placoderms, which were dominant in the Early–Middle Devonian seas.
During the Early Devonian, the sarcopterygian line split into two main lineages: the coelacanths and the Rhipidistia.

The coelacanths appeared in the Early Devonian, and stayed in the oceans. The coelacanths" heyday was the Late Devonian and Carboniferous, as they were more common during those periods than in any other period in the Phanerozoic. Coelacanths still live today in the oceans.
Rhipidistians appeared about the same time as the coelacanths, but unlike them, rhipidistians left the ocean world and migrated into the freshwater habitats; their ancestors probably lived in the oceans near the river mouths (estuaries). The rhipidistians, in turn, split into two major groups: the lungfishes, and the tetrapodomorphs.
The lungfishes" greatest diversity was in the Triassic period, but today, there are fewer than a dozen genera left. The lungfishes evolved the first proto-lungs and proto-limbs. The lungfishes, ancient and modern, are adapted to use their stubby fins (proto-limbs) to walk on land and find new water if their waterhole is depleted, and use their lungs to breathe air and get sufficient oxygen.
The tetrapodomorphs have the same basic anatomy as the lungfishes, who were their closest kin, but the tetrapodomorphs appear to have inhabited water a little longer, until the Late Devonian. Tetrapods, four legged vertebrates, were the terapodomorphs" descendants. Tetrapods appeared in the Late Devonian epoch.
Non-tetrapod sarcopterygians continued to survive towards the end of Paleozoic era. They suffered heavy losses during the Permian-Triassic extinction event.
Most lobe-fins belong to one of three major groups: the Actinistia (coelacanths), the Dipnomorpha (lungfishes and Porolepiformes), and the Tetrapodomorpha (Rhizodontoformes, Osteolepiformes and Elpistostegalia). Less diverse groups include the Onchodontida (three Devonian genera) and two Lower Devonian genera (Powichthys and Youngolepis) that show some affinity to the Dipnomorpha.

Coelacanthimorpha

1. Mawsonia 2. Coccoderma 3. Axelrodichthys 4. Caridosuctor 5. Allenypterus
The Actinistia first appear in the Middle Devonian and become relatively diverse during the Carboniferous, decline in the Permian and again become diverse in the Triassic. They apparently decline through the remainder of the Mesozoic, with the last fossil record occurring in the Late Cretaceous. Actinistians were thought to have become extinct until the spectacular discovery of Latimeria chalumnae in 1938.

Dipnoi

1. Dipterus 2. Youngolepis 3. Laccognathus 4. Ceratodus 5. Retodus
The Dipnomorpha contain the Porolepiformes and the Dipnoi (lungfishes). Porolepiforms were relatively large (1-2.5 m) fishes that were prominent predators in Middle and Late Devonian nearshore and freshwater habitats. One member, Holoptychius (shown above), has been collected in several Devonian tetrapod localities. Lungfishes are among the first lobe-fins to appear in the fossil record. Their diversity peaks in the Upper Devonian, but a second diversity maxima occurs in the Triassic. Lungfishes and the Actinsitia are the only two groups of lobe-fins to have survived the Permian; both also have living representatives.

Lobe-finned Osteolepidiformes

1. Elginerpeton 2. Panderichthys 3. Tiktaalik 4. Eusthenopteron 5. Osteolepis
Extinct lobe-finned fish that first appeared during the Devonian period including Osteolepidiformes, Elpistostegalia, and Elginerpetontidae.
Osteolepiformes is the group of lobe-fins that gave rise to the tetrapods. They first appeared in the late Lower Devonian or early Middle Devonian and reached a maximum diversity in the Late Devonian. The order contains a number of fishes of uncertain phylogeny and two monophyletic families, the Megalichthyidae and the Tristichopteridae.The Megalichthyids is the only osteolepiform group to survive past the end of the Devonian. Tristichopterids apparently gave rise to the tetrapods and the Elpistostegalids.

Rhizodontimorpha

1. Strepsodus 2. Gooloogongia 3. Rhizodus 4. Letognathus 5. Sauripterus
Extinct predatory lobe-finned fish that lived in tropical rivers and freshwater lakes during the Devonian and Carboniferous periods.Rhizodonts first appeared in the Middle Devonian and developed into the giants (2-7 m) of freshwater habitats from the latest Devonian through the Carboniferous and into the Lower Permian.

Porolepimorpha

1. Gyroptychius 2. Holoptychius 3. Glyptolepis 4. Porolepis
Extinct prehistoric lobe-finned fish that lived during the Devonian period.

Other Sarcopterygians

1. Qingmenodus 2. Psarolepis 3. Strunius 4. Grossius 5. Onychodus
Consolidate small Sarcopterygian families (e.g., Onychodontida) along with genera of uncertain placement within the Sarcopterygii class.


The largest of these was the 6 metres (20 ft) long Rhizodus.

Rhizodus (Root tooth) is an extinct genus of rhizodont, a branch of the Sarcopterygii, the bony vertebrate clade that also includes tetrapods. It was of enormous size, reaching 6–7 m in length.The most notable characteristics of Rhizodus, when compared to other giant lobe-fins such as Barameda, were the two giant 22 cm fangs located near the front of its jaws followed by other teeth scaling downwards in size. Rhizodus was a giant apex predator that resided in freshwater lakes, river systems and large swamps in the entire Carboniferous period, feeding on small to medium sized amphibians (ranging from 30 cm and 600 cm in size), using its teeth to kill prey and rip it into digestible sizes, rather than swallowing prey whole like other, smaller-toothed sarcopterygii.

Barameda mitchelli

Hyneria

As a lobe finned fish, Hyneria would have looked like a larger version of Eusthenopteron. It had powerful fins, but the popularised image of Hyneria using them to crawl across land is to date only speculation. It’s likely that they would have been of more use while navigating shallow waters and submerged obstacles. In terms of being a predator, Hyneria would have been predators of other fish including sharks as well as temnospondyl amphibians.
The size of Hyneria has been open to a lot of debate over the years. In the 2005 series Walking with Monsters Hyneria was portrayed as a five meter long fish, though where this size estimate came from is uncertain, and is also questionable given the that the Walking With... series of shows tend to have a history of overestimating the size of prehistoric creatures (such as the portrayal of the pliosaur Liopleurodon being twenty-five meters long when the largest specimen is only seven, or the pterosaur Ornithocheirus presented with a twelve meter wingspan when fossils indicate a six meter wingspan). The actual fossils of individual Hyneria actually point to a more modest size of between two and four meters long. If you have come to this page expecting to find a really large lobe-finned fish, then you should check out the genus Rhizodus, a giant six to seven meter long predator.

Edenopteron

Edenopteron is a genus of large tristichopterid fish from the Late Devonian (Famennian) of what is now southeastern Australia. It is known from a single specimen of a single species, E. keithcrooki, described in 2013.
Edenopteron keithcrooki is known from remains excavated from the Worange Point Formation, near the town of Eden on the coast of New South Wales in 2008. The species name is a combination of the name Eden and pteron, meaning wing or fin in Greek. The specific name honors Dr. Keith Crook of the Australian National University for his discovery of several fossil sites in New South Wales.
The holotype consists of numerous semi-articulated remains, including an incomplete skull roof, snout, palate, cheeks, lower jaws and associated dermal bones, a left shoulder girdle, and assorted scales. Reconstructions suggest a skull length of 30 cm (12 in) and lower jaw length of about 48 cm (19 in). The endoskeleton shows a large or complete lack of ossification. The orbits (eye-sockets) are somewhat triangular rather than oval-shaped. Edenopteron possessed dentary fangs and premaxillary tusks, which are presumed to be derived traits for other large tristichopterids. By comparison to body size ratios of other tristichopterid fishes (e.g. Eusthenodon, Langlieria, Mandageria), the body length of Edenopteron is estimated at 2.9—3.2 m (9.5—10.5 ft).Additional fossil material may be described in the future: according to lead researcher Gavin Young, quoted in the Canberra Times: "We know that part of the pectoral girdle is still in the rock, so if we can lift up a few more blocks, we might find that the body is actually preserved in the rock

Coelacanthiformes


Mawsonia  gigas-Up to 4 meters long, though isolated fossils suggest that rare individuals may have grown slightly larger than this.
Mawsonia is an extinct genus of prehistoric coelacanth fish, and the largest of this group, up to several metres long.It lived during the Cretaceous period (Albian stage, about 99 to 112 million years ago). Fossils have been found in Africa and South America. Mawsonia was first described by British palaeontologist Arthur Smith Woodward in 1907.
Coelacanths are one of the few creatures that typify animal life in the Mesozoic that are still alive today. Modern coelacanths are represented by the genus Latimeria that live in the deep waters of the Indian Ocean, the largest examples of which are known to easily attain lengths of two meters. Back in the early Cretaceous however these fish would have been small fry, with impressively large coelacanths of the Mawsonia genus reaching lengths of up to four meters, double that of the largest observed Latimeria. Because of their large size, Mawsonia are rarely preserved complete, and specimens which are preserved, are usually of smaller individuals under three meters. Skull bones are usually the most common specimens of Mawsonia due to the greater bone density increasing the likelihood of those parts surviving long enough to fossilize.
Mawsonia like other coelacanths were probably predatory fish that would cruise over the sea floor snatching up fish and larger invertebrates that were sheltering in crevices amongst rocks and coral. We do not know for certain however if Mawsonia were nocturnal like the Latimeria coelacanths that we know today. Interestingly, Mawsonia may have been more inclined to stray into shallower waters than what Latimeria are known to. This is because most of the fossil bearing formations that Mawsonia are known from were estuarine and mangrove habitats back in the early Cretaceous.
When fully grown to such a large size, Mawsonia may have had few predators, though larger sharks, pliosaurs and perhaps even spinosaurid dinosaurs, may have still been potential dangers for Mawsonia.