| Gyracanthides Temporal range: Devonian–Carboniferous | |
|---|---|
 | |
| Life restoration | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | † Acanthodii |
| Order: | † Climatiiformes (?) |
| Family: | † Gyracanthidae |
| Genus: | † Gyracanthides Woodward, 1906 |
| Type species | |
| †Gyracanthides murrayi Woodward, 1906 | |
| Other species | |
Gyracanthides is an extinct genus of acanthodian gnathostome, known from Devonian to Early Carboniferous. [2] [3]
Gyracanthides is large acanthodian, G. murrayi reached the length up to 1.2 m (3 ft 11 in). The pectoral fin spines are large compared to its body, for specimen that have estimated to be 90 cm (35 in) had pectoral fin spines around 40 cm (16 in) long. [2] A recent study suggested that Gyracanthides is closely related to chondrichthyans (as currently delimited), and that acanthodians are paraphyletic. [4]
Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
Acanthodii or acanthodians is an extinct class of gnathostomes. They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras. Acanthodians possess a mosaic of features shared with both osteichthyans and chondrichthyans. In general body shape, they were similar to modern sharks, but their epidermis was covered with tiny rhomboid platelets like the scales of holosteians.
Cladoselache is an extinct genus of shark-like chondrichthyan from the Late Devonian (Famennian) of North America. It was similar in body shape to modern lamnid sharks, but was not closely related to lamnids or to any other modern (selachian) shark. As an early chondrichthyan, it had yet to evolve traits of modern sharks such as accelerated tooth replacement, a loose jaw suspension, enameloid teeth, and possibly claspers.
Stethacanthus is an extinct genus of shark-like cartilaginous fish which lived from the Late Devonian to Late Carboniferous epoch, dying out around 298.9 million years ago. Fossils have been found in Australia, Asia, Europe and North America.
Climatius is an extinct genus of spiny shark. This genus is known from the Early Devonian (Lochkovian) of Europe, previously considered Silurian remains actually belong to Nostolepis instead.
Acanthodes is an extinct genus of acanthodian fish. Species have been found in Europe, North America, and Asia, spanning the Early Carboniferous to the Early Permian, making it one of the youngest known acanthodian genera.
The Climatiiformes is an order of extinct fish belonging to the class Acanthodii. Like most other "spiny sharks", the Climatiiformes had sharp spines. These animals were often fairly small in size and lived from the Late Silurian to the Early Carboniferous period. The type genus is Climatius. The order used to be subdivided into the suborders Climatiida and Diplacanthida, but subsequently Diplacanthida has been elevated to a separate order, the Diplacanthiformes. The Diplacanthiformes take their name from Diplacanthus, first described by Agassiz in 1843. Family Gyracanthidae is sometimes rejected from this order.
Cheiracanthus is an extinct genus of a group of fish called Acanthodii. It was a deep-bodied acanthodian about 12 in. (30 cm) in length. It had a blunt head, upturned tail, and fins protected by spines. Unlike many other acanthodians, it had one, solitary dorsal fin. Cheiracanthus swam at mid-depth in lakes and rivers, seizing small prey in its gaping jaws. Whole fossils of this fish occur only in Mid-Devonian rocks in Scotland, but its distinctive small, ornamented scales crop up around the world, as far south as Antarctica.
Barameda is a genus of rhizodont lobe-finned fishes which lived during the Tournaisian stage near the start of the Carboniferous period in Australia; fossils of the genus have been reported from the Snowy Plains Formation. The largest member of this genus, Barameda decipiens, reached an estimated length of around 3–4 metres (9.8–13.1 ft), while smallest species, B. mitchelli is estimated to have had a length of about 35 centimetres (14 in).
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays (Neoselachii) as part of the clade Euselachii. They are distinguished from other chondrichthyans by their distinctive fin spines and cephalic spines present on the heads of males. An ecologically diverse group, they were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct.
Ischanacanthiformes is a prehistoric order of "acanthodian" stem-chondrichthyans found in Canada, Ukraine and United Kingdom. Members of this order were nektonic carnivores, eating animals that swim rather than plankton. They had slender builds, light armor, deeply inserted spines, shark-like teeth, and two dorsal fins. Some species were around 2 meters long. It was described by Berg in 1940.
Brochoadmones is an extinct genus of acanthodian from the Devonian of what is now Canada. It is the only genus in the suborder Brochoadmonoidei, whose relationship to other acanthodian orders remains currently in flux.
The Battery Point Formation is a geologic formation in Quebec. It preserves fossils dating back to the early Emsian to early Eifelian the lower Devonian period.
The York River Formation is a geologic formation in Quebec. It preserves fossils dating back to the Devonian period.
The Campbellton Formation is a geologic formation in New Brunswick. It preserves fossils dating back to the latest Pragian and Emsian of the Devonian period.
Ptomacanthus is an extinct genus of spiny shark, an early relative of living cartilaginous fishes.
Gyracanthidae is an family of extinct fish belonging to the class Acanthodii, known from early Devonian to late Carboniferous. Members are characterized by large, broad-based, paired fin spines with the pectoral fin spines having a distinct longitudinal curvature. Although it is originally classified in order Climatiiformes, but later study questioned this.
Lebachacanthus is a genus of extinct xenacanth cartilaginous fish known from the late Carboniferous-Early Permian of Europe. During the late Paleozoic, xenacanths were the apex predators of freshwater ecosystems, preying on small amphibians.
Qianodus is a jawed vertebrate genus that is based on disarticulated teeth from the lower Silurian of China. The type and only species of Qianodus, Q. duplicis, is known from compound dental elements called tooth whorls, each consisting of multiple tooth generations carried by a spiral-shaped base. The tooth whorls of Qianodus represent the oldest unequivocal remains of a toothed vertebrate, predating previously recorded occurrences by about 14 million years. The specimens attributed to the genus come from limestone conglomerate beds of the Rongxi Formation exposed near the village of Leijiatun, Guizhou Province, China. These horizons have been interpreted as tidal deposits1 that form part of the shallow marine sequences of the Rongxi Formation.
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