Ornithoprion

Last updated

Ornithoprion
Temporal range: Pennsylvanian (Moscovian), 315.2–307  Ma
Ornithoprion skeletal.png
Skeletal reconstruction of Ornithoprion, with known material represented in white and implied/suggested material represented in gray
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Holocephali
Order:† Eugeneodontida
Family:† Caseodontidae
Genus:† Ornithoprion
Zangerl, 1966
Type species
Ornithoprion hertwigi
Zangerl, 1966

Ornithoprion is a genus of extinct cartilaginous fish in the family Caseodontidae . The only species, O. hertwigi, lived during the Moscovian stage of the Pennsylvanian, between 315.2 to 307 million years ago, and is known from black shale deposits in what is now the Midwestern United States. The discovery and description of Ornithoprion, performed primarily via radiography, helped clarify the skull anatomy of eugeneodonts; a group which includes O. hertwigi and which were previously known primarily from isolated teeth. The genus name, which is derived from the ancient Greek órnith- meaning 'bird' and príōn meaning 'saw', was inspired by the animal's vaguely bird-like skull and the saw-like appearance of the lower teeth. The species name honors Oscar Hertwig.

Contents

Ornithoprion is unique among known eugeneodonts in possessing an extremely elongated structure connecting to the lower jaw, known as the mandibular rostrum, which was protected by a beak of fused bony scales and which the precise function of is not known. It inhabited shallow marine environments and coexisted with a variety of other cartilaginous fishes. The structure of Ornithoprion's teeth suggests that it was a durophage which hunted marine invertebrates, and bite marks and damage to its fossils indicate it was fed on by other carnivores. The total length is uncertain due to the rear portion of the body being missing in all known specimens, but the largest skulls are approximately 10 cm (3.9 in) in length.

Discovery and naming

Stratigraphy of the Illinois Basin, where O. hertwigi's fossils have been found Illinois Basin Pennsylvanian stratigraphy.jpg
Stratigraphy of the Illinois Basin, where O. hertwigi's fossils have been found

The genus and species were named and described in 1966, by geologist Rainer Zangerl, in a paper published by the Field Museum of Natural History (then the Chicago Museum of Natural History). [1] This description was based on material collected primarily from the Mecca Quarry of Indiana, in rocks which are part of the Linton Formation. A single specimen was also collected from the Logan Quarry in an exposure of the Staunton Formation, also in Indiana, and another from a coal mine near Wilmington, Illinois. All specimens are preserved in organic black shales, with the Illinois specimen being described as pyritic. [2] The Mecca and Logan Quarry material has been dated to the Moscovian or Desmoinesian stage of the Pennsylvanian, [3] [1] which is part of the Carboniferous period and which lasted from 315.2 to 307 million years ago. [4] The precise age and locality of the Illinois specimen is unknown due to it being held in a private collection. Nine specimens were initially described, with CNHM PF-2710 (now FMNH PF-2710) from the Mecca Quarry being designated as the holotype. [2] [5] Multiple additional specimens have subsequently been assigned to Ornithoprion, including occurrences from the Excello Shale of Indiana. [6] [7] [8]

Like many other chondrichthyans from the Mecca and Logan quarries, [9] [10] the studies of the holotype and paratypes of Ornithoprion were primarily performed by radiographic imaging. [2] [11] The specimens were not extracted from the surrounding matrix, but were instead stereoscopically scanned via X-rays, with the calcified elements of their skeletons appearing clearly against the shale. The captured images were subsequently printed and illustrated. The Staunton Formation specimen, FMNH PF-2656, was also cut into multiple cross-sections, with these being studied to reveal the internal anatomy of the dermal denticles and teeth. At the time of its discovery, Ornithoprion represented one of the best preserved eugeneodonts, and one of the few known from postcranial fossils. [2]

The genus name may be literally translated as 'bird saw', [11] and derives from the ancient Greek roots órnith- (ὄρνιθ-) meaning 'bird' and priōn (πρίων), meaning 'saw'. [12] [13] The suffix -prion is a common component in the names of eugeneodont fishes and is in reference to the saw-like form of their symphyseal (midline) tooth whorls, [11] [14] : 70–93  while ornithos in this case refers to the animal's uniquely bird-like skull. [2]

Description

Life restoration of Ornithoprion hertwigi depicted with five gill slits, a fusiform body, and a lack of pelvic and anal fins Ornithoprion hertwigi.png
Life restoration of Ornithoprion hertwigi depicted with five gill slits, a fusiform body, and a lack of pelvic and anal fins

O. hertwigi is known from multiple articulated but incomplete specimens, with none preserving skeletal material beyond the pectoral girdle. Most of these specimens are preserved in lateral view, and all, including the holotype, are heavily compressed. [2] [1] As in other eugeneodonts, [15] the preserved portion of the skeleton was composed primarily of cartilage reinforced by mineralized prismatic tesserae; [2] hexagonal structures which strengthen the cartilage and are also present in the skeletons of modern Elasmobranchs (sharks and rays). [16] While the postcranial anatomy is incompletely known, it was likely similar to other caseodontids such as Fadenia and Romerodus , with a streamlined body, a homocercal (crescent-shaped) caudal fin, and reduced or absent pelvic fins. [7] [17] The presence or absence of pelvic claspers in eugeneodonts is unknown, and it is debated if they possessed them in life. [14] : 167–169  The dorsal and pectoral fins of Ornithoprion are also unknown, but there is no indication they possessed fin spines like those seen in many other Carboniferous chondrichthyans. [7] [18] At least five branchial arches are present, [17] although as with other eugeneodonts it remains unclear if these supported individual gill slits or an operculum (plate-like cover). [14] : 143–144, 167  The total body length is uncertain due to the incomplete nature of the fossils, although the largest skull measures approximately 10 cm (3.9 in). [18] American illustrator Ray Troll has proposed a total length of 60 cm (2 ft), although his reconstruction gives the species an elongated, eel-like body, [19] which is not phylogenetically supported. [7] [14] : 144  An estimate as high as 90 cm (3 ft) has been suggested by author Richard Ellis, based on an assumed skull length of 15 cm (6 in) which is larger than the largest described material. [11] [18]

Skull

Restored skull of Ornithoprion hertwigi scaled to the largest figured specimen. Thin lines along the rostra represent rods of armor Ornithoprion skull.png
Restored skull of Ornithoprion hertwigi scaled to the largest figured specimen. Thin lines along the rostra represent rods of armor

The most diagnostic trait of Ornithoprion is the exaggerated rostrum extending from the lower jaw, which is nearly the length of the rest of the skull. The rostrum, as well as a corresponding section of the skull, was armored and reinforced by rods of bone, [18] [20] which appear to have been dermal structures formed separately from the underlying cartilage or tesserae. [8] The mandibular rostrum is connected to the Meckel's cartilage (lower jaw) by an unfused joint, with a single whorl of teeth positioned along the midline of the rostrum, near the point of contact with the lower jaw. Below the whorl, a keel of cartilage protrudes from the bottom of the rostrum. The tip of the rostrum is extremely elongated, and according to Zangerl's description was likely to have been cylindrical in cross section and spear-like in life. [2] There is no evidence that sensory structures were present within the rostrum. [21] The Meckel's cartilage consists of a pair of thin, flattened cartilage plates which support the rostrum and which attach to the palatoquadrates. [7] [8]

Restored skull of the distantly related Helicoprion davidsii, displaying well-developed palatoquadrates and a lack of a mandibular rostrum Helicoprion skull diagram (NP).png
Restored skull of the distantly related Helicoprion davidsii , displaying well-developed palatoquadrates and a lack of a mandibular rostrum

The cranium is long and pointed and possesses large eye sockets, a condition which vaguely resembles the skull of a bird and inspired the name of the genus. An indentation set far forward on the snout is reported by Zangerl to have likely held the nasal capsule, [2] although the latter is unpreserved. The palatoquadrates, which typically form the upper jaw of living cartilaginous fish, are reduced and immobile, and articulate with the cranium in a greatly limited, autodiastylic (two jointed) manner. [7] The reduced state differs greatly from that of the eugeneodont Helicoprion in which the palatoquadrates are large and specialized, [15] [22] and potentially from Sarcoprion , which may have had them fused to the cranium or lost entirely. [7] [8] The palatoquadrate seen in Ornithoprion is most similar to that seen in other caseodonts such as Caseodus , which typically share its thin, band-like shape and limited cranial articulation. [7] The remains of what Zangerl speculated to be part of the hyoid arch are also present along the back of the skull. [2]

Teeth

The lower teeth of O. hertwigi consist of both multiple large tooth crowns extending from a connected root, known as a tooth whorl, [23] and tooth batteries (tightly-stacked rows of crushing teeth) down the length of the lower jaw. The crushing teeth are plate-like, flattened, rectangular, and possessed deep pits and grooves in their surface. [8] They formed a flattened "tooth pavement" in life; likely used for processing shelled prey and similar to that of many other Paleozoic chondrichthyans. [7] [8] The structure of these pavement teeth was directly compared with those of Erikodus, a related genus, in Zangerl's 1966 description. [2] The lower tooth whorl, a characteristic trait of the eugeneodonts, possessed up to seven broad, rounded, bulbous tooth crowns and was positioned along the midline of the body. [7] The tooth crowns on the lower whorl vary in size, with the smallest teeth being situated at the front of the whorl and the largest at the back. [2] [7] It is thought that both another battery of pavement teeth and larger, pointed V-shaped teeth were attached directly to the underside of the cranium. [8] These V-shaped teeth are thought to have formed another symphyseal (midline) tooth whorl similar to that proposed in Sarcoprion, [7] although their precise arrangement in life is not known. [2] Based on thin sectioning, the teeth of Ornithoprion were composed primarily of trabecular dentin (a spongy form of dentin present in holocephalan fishes) with an outer coating of orthodentin. [2] [18] [8] There is no indication of enameloid (vitrodentin), but a small layer may have been present in life. [2] [7]

Postcranial skeleton

Illustrated diagram of the holotype, with damaged or poorly defined anatomy represented by dashed lines. Disarticulated teeth and denticles have been omitted for anatomical clarity Ornithoprion holotype.png
Illustrated diagram of the holotype, with damaged or poorly defined anatomy represented by dashed lines. Disarticulated teeth and denticles have been omitted for anatomical clarity

The known postcrania of Ornithoprion encompass the frontmost portion of the skeleton. The left and right scapulocoradoids (pectoral girdle) are not fused to each other, unlike living chondrichthyans, and had a forward-angled scapular portion. [2] [18] Either five or six pairs of ceratobranchials (gill arches) are present, [17] with what Zangerl tentatively identifies as sternal cartilage running beneath them. [2] [18] [24] This unpaired intercoracoidal cartilage has also been identified in living broadnose sevengill sharks, [25] as well as the extinct iniopterygians, the Jurassic chimaeriform Ischyodus, [24] and potentially the closely related Fadenia. [17] The function of this structure in Ornithoprion is unknown, although it is likely homologous to similar, paired cartilage structures observed in other extinct chondrichthyans. [7]

The vertebral centra of Ornithoprion are not preserved and were likely uncalcified, although a series of diamond-shaped cartilage structures are present along the expected path of the vertebral column. These cartilage structures may represent heavily modified neural arches, the anatomy of which is unique to O. hertwigi. These specialized neural arches may be an adaptation associated with the morphology or function of the animal's pointed skull and rostrum. [2]

Dermal denticles

Unlike living chimaeras, in which dermal denticles (also called placoid scales) are only present in isolated regions, [16] the known body of Ornithoprion was completely covered in tiny, rounded, [26] tooth-like denticles similar to those of sharks. [2] These denticles possessed a pulp cavity, were predominantly made up of orthodentin, and grew from a flattened base, much like those of modern cartilaginous fish. However, the bases of the denticles may have been composed of bone rather than a form of dentin, [2] [20] [18] and many denticles form fused, compound structures. These compound denticles, termed "polydontode scales", share a single base with multiple crowns and pulp cavities emerging from it, and in O. hertwigi may consist of more than seven crowns. [2] Similar polydontode scales are known to occur in the related Sarcoprion and potentially Helicoprion, [26] although it has not been noted that these contain bone. If Zangerl's interpretation of the dermal structures of O. hertwigi is correct, it would represent a rare example of bone among extinct euchondrocephalans, which otherwise have denticles and armor composed of dentin. [16] Extremely small denticles were also present in the mouth and throat, which were exclusively composed of orthodentin. [2]

In his original 1966 description, Zangerl speculates that the reinforcing "beak" of bony rods present on the snout and rostrum were formed by the compounding of these polydontode scales. He likens this phenomenon to that proposed by Oscar Hertwig as an explanation for the origin of vertebrate dermal armor, and although Zangerl acknowledges that this adaptation evolved independently in Ornithoprion, he honors Hertwig in the name of the type species. [2]

Classification

While today represented only by a single order (Chimaeriformes) the subclass Holocephali was far more diverse during the Paleozoic. Pictured, from top to bottom: Cobelodus, Heteropetalus, Falcatus, Harpagofututor, and a fetal Delphyodontos (not to scale) Fossil Holocephali (Cobelodus, Heteropetalus, Falcatus, Harpagofututor, and Delphyodontos).jpg
While today represented only by a single order (Chimaeriformes) the subclass Holocephali was far more diverse during the Paleozoic. Pictured, from top to bottom: Cobelodus , Heteropetalus , Falcatus , Harpagofututor , and a fetal Delphyodontos (not to scale)

Though often referred to as sharks in both formal and informal texts, the eugeneodonts are likely only distant relatives of living sharks. In its initial description by Rainer Zangerl, Ornithoprion was placed as a member of Edestidae within the order (sometimes class) Bradyodonti. [2] [16] [26] In the 1971 edition of Paleozoic Fishes, researcher R. S. Miles considered the genus to be of uncertain position within Chondrichthyes, and tentatively placed it within Holocephali. He suggested that its similarities to edestids might be the result of convergent evolution (independent evolution) due to differences in the anatomy of the gills, the tooth histology, and the palatoquadrates. [18] In 1981, Zangerl considered O. hertwigi as a member of Caseodontidae, as part of the larger superfamily Caseodontoidea and the newly established order Eugeneodontida, in light of the numerous new taxa and characteristics that had been observed since Ornithoprion's original description. In this publication, however, he considered the newly christened eugeneodonts to be members of the Elasmobranchii rather than the traditionally assumed Holocephali or Bradyodonti. [7] During the 1990's edestid specialist Svend Erik Bendix-Almgreen, in his personal communications with artist Ray Troll, expressed belief that the features used to unite the Eugeneodontida may be the result of convergent evolution and that the group as defined by Zangerl was likely polyphyletic (not a natural group). [14] : 108–109  Bendix-Almgreen had expressed a similar attitude in earlier publications throughout the 1960's and 1970's, in these cases supported primarily by the apparent presence or absence of enameloid or vitrodentin between different edestid taxa, [27] [7] or differences in the features of their skulls. [28]

Today, while Zangerl's classification of eugeneodonts as elasmobranchs is no longer supported, [15] [22] [23] his erected suborders and families within the group remain in use. [17] [8] [29] Eugeneodontida is regarded as a monophyletic group on the stem of subclass Holocephali (sometimes defined as the more broadly-encompassing Euchondrocephali) [8] [29] and as part of the class Chondrichthyes, [23] [30] with the discrepancies in tooth histology previously used to argue against their close relation being explained by different members' variable rates of tooth replacement or wear. [7] The only extant members of the Euchondrocephali are three families of chimaeras, all of which are highly specialized deep-water fish and are not closely comparable to eugeneodonts in anatomy or lifestyle. [14] In the absence of living analogues, the higher level interrelationships between extinct members of the subclass remain enigmatic. [31] Eugeneodontia has been suggested to be most closely related to (or potentially descended from) the Orodontiformes, a group of Devonian-Carboniferous euchondrocephs with similar dentition. [8] [32] [33]

The skull and vertebral morphology of Ornithoprion is very different from that of other known eugeneodonts, [7] [17] and key elements of the postcranial skeleton are missing. [2] Its classification within the Caseodontidae is based on the bulbous, rounded nature of its tooth crowns and reduction of its palatoquadrates, features which are also found in related genera such as Caseodus. [7] [8] [29] Below is a cladogram as illustrated by Zangerl (1981) based on morphological traits, which places Ornithoprion as a basal member of a clade also containing Erikodus and Fadenia. [7]

Paleoecology and paleobiology

Habitat and ecological niche

The holotype of Orodus greggi, discovered at the Logan Quarry, on display at the Field Museum of Natural History Orodus greggi FMNH.jpg
The holotype of Orodus greggi, discovered at the Logan Quarry, on display at the Field Museum of Natural History

The Mecca, Logan, and Excello shales all represent marine depositional environments, and all preserve a diverse assemblage of species. [34] [9] [35] In a 1963 publication, researchers Rainer Zangerl and Eugene Richardson proposed that the Mecca and Logan sites were extremely shallow habitats, likely less than a meter (3.3 ft) of water, with small, isolated deeper areas. [36] The presence of peat and coal indicates that the deposits overlay drowned forests and are a recent transgression of a marine environment over a terrestrial one (known as a cyclothem). The rich, black, fissile shale which encases the fossils indicates massive amounts of decaying organic material such as algae were present, which led to anoxic conditions and formed organic mud. Zangerl and Richardson also suggest that there is evidence of water levels lowering significantly during the dry season, often isolating fishes into small saltwater ponds or "fish traps" and creating ideal conditions for preservation. [9] The Logan and Mecca environment likely only existed for a brief period, with overlying invertebrate communities and limestone deposits indicating that deeper water eventually flooded the region and created a more stable habitat. [36] The presence of larger fish and cephalopods at the Logan Quarry site may suggest somewhat deeper waters. [9] [36] Some subsequent authors have suggested that these shales were in fact formed in deep-water environments with anoxic mud bottoms, similar to the conditions seen in many other fossiliferous midwestern shales, [37] [38] although other later authors have treated the conditions that formed the Mecca and Logan sites as distinct from those that formed deep-sea shales such as the Stark Shale and continued to accept a shallow water environment. [36] [39]

The larger, distantly-related edestoid Edestus (pictured) cohabited with Ornithoprion and may have been among its predators Edestus recon.png
The larger, distantly-related edestoid Edestus (pictured) cohabited with Ornithoprion and may have been among its predators

Ornithoprion fossils often contain a number of other remains in the same shale slabs, although in different bedding planes and not directly associated. These include isolated spines and denticles from acanthodians, Listracanthus , and Petrodus. [2] The Mecca fauna, which includes both the Mecca and Logan Quarry sites, also preserves an assemblage of conodonts, [36] palaeoniscoids, brachiopods, orthocones, and cartilaginous fishes such as Orodus , Denaea , Cobelodus , Symmorium , and other holocephalans, including members of Iniopterygii. [34] [9] The Logan Quarry was inhabited by, in addition to many chondrichthyans, an unnamed chondrost-like actinopterygian with a similarly elongated rostrum, which was entirely unrelated to Ornithoprion. [21] Invertebrates such as brachiopods and ammonoids are known from the Excello Shale, as are a wide variety of cartilaginous fishes including Listracanthus, Caseodus, Edestus, and Stethacanthus , all of which were roughly contemporaneous with Ornithoprion. [35]

Evidence of predation

Numerous specimens of O. hertwigi show damage which Zangerl interprets as feeding traces left by predators or scavengers. Portions of the skeleton are often broken, maimed or missing, and it has been suggested that the unpreserved rear halves of the animals may have been severed by predation attempts. [2] In a 2019 publication, author Wayne Itano suggests that the bisected fish remains of the Mecca and Logan shales, such as the known fossils of O. hertwigi, may be the result of a novel feeding method displayed by the contemporaneous and much larger Edestus, which cut prey in half in a manner similar to modern sawfish. [40] The skulls of several Ornithoprion specimens also display crushed or missing chunks, which are proposed to have resulted from other fishes biting them and fracturing the cartilage. [2] Coprolites and fossilized pellets containing fish remains are often found in the same formations as Ornithoprion and were likely produced by larger predators. [9]

Diet and proposed feeding methods

The skull of the Cretaceous actinopterygian Saurodon, which Rainer Zangerl considers the closest morphological analogue for the rostrum of Ornithoprion Saurodon Sternberg skull.jpg
The skull of the Cretaceous actinopterygian Saurodon , which Rainer Zangerl considers the closest morphological analogue for the rostrum of Ornithoprion

Similar to many of its close relatives, [41] [42] Ornithoprion is believed to have been a durophage that fed on benthic invertebrates. The rounded, bulbous crowns of the lower symphyseal whorl appear to be an adaptation for crushing, [2] [19] and the remains of brachiopod shells are known from the stomach of the related Fadenia. [42]

The mandibular rostrum is believed to have been utilized in feeding, although the exact mechanism is unclear. Zangerl, in 1966, proposes that it was used to disturb or probe sediment while hunting for prey living on or within the seabed, and, potentially, flinging dislodged prey into the water column. He notes that this possible feeding mode is entirely speculative, [2] although a later study agrees with the conclusion that the rostra of caseodonts could have been used to dislodge brachiopods. [42] The anatomy of the rostrum is inconsistent with its use as a sensory structure due to the lack of grooves and pits to house electroreceptors. [21] Some features of the animal's skull, such as the armor and articulation of the upper and lower jaws, are suggested by Zangerl to be shock-absorbing adaptations, although he considers it unlikely that the rostrum was used as a weapon. The mandibular rostrum of Ornithoprion has been compared with those of the unrelated extinct bony fish Saurodon and Saurocephalus , in which the function is also not confidently known. [2]

Use in reconstructing Helicoprion

Because of its phylogenetic proximity, Ornithoprion has been used as a basis for restoring the anatomy and physiology of other eugeneodonts. Ray Troll, an Alaskan illustrator, has cited the taxon as one of his references while reconstructing the potential close relative and more widely publicized genus Helicoprion. [14] : 144, 151  Both murals and a life-sized model of Helicoprion davidsii, designed by Troll and displayed at the Idaho Museum of Natural History, [43] directly reference features of O. hertwigi such as gill anatomy. [14] : 151  [15] The genus is also cited as one of the taxa which indicated the position of Helicoprion's whorl in the lower jaw prior to descriptions of its own fossils becoming available. Edestid researcher Bendix-Almgreen had, however, criticized the use of caseodonts as the basis for Helicoprion in Troll's art, as he believed they did not represent close phylogenetic or ecological analogues. [14] : 108, 109 

See also

Related Research Articles

<span class="mw-page-title-main">Chondrichthyes</span> Class of jawed cartilaginous fishes

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.

<span class="mw-page-title-main">Chimaera</span> Cartilaginous fish in the order Chimaeriformes

Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.

<i>Cladoselache</i> Extinct genus of chondrichthyans

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.

<i>Helicoprion</i> Genus of fossil fishes

Helicoprion is an extinct genus of shark-like eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most extinct cartilaginous fish, the skeleton is mostly unknown. Fossils of Helicoprion are known from a 20 million year timespan during the Permian period from the Artinskian stage of the Cisuralian to the Roadian stage of the Guadalupian. The closest living relatives of Helicoprion are the chimaeras, though their relationship is very distant. The unusual tooth arrangement is thought to have been an adaption for feeding on soft bodied prey, and may have functioned as a deshelling mechanism for hard bodied cephalopods such as nautiloids and ammonoids. In 2013, systematic revision of Helicoprion via morphometric analysis of the tooth whorls found only H. davisii, H. bessonowi and H. ergassaminon to be valid, with some of the larger tooth whorls being outliers.

<i>Stethacanthus</i> Extinct genus of cartilaginous fishes

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.

<i>Cobelodus</i> Extinct genus of cartilaginous fishes

Cobelodus is an extinct genus of cartilaginous fish known from the late Carboniferous to the early Permian period. The type specimen, assigned to the genus Styptobasis, was discovered by Edward Drinker Cope in Illinois Basin black coal shales. Rainer Zangerl reassigned S. aculeata in 1973 to the genus Cobelodus, translating to 'needle tooth'. Cope's description was based from a tooth fragment and was compared to the genus Monocladodus. Cobelodus differs from Styptobasis and Monocladodus in the anatomy of its teeth and pectoral fins.

<i>Edestus</i> Extinct genus of eugeneodontid fish

Edestus is an extinct genus of eugeneodontid holocephalian fish known from the Late Carboniferous (Pennsylvanian) of the United Kingdom, Russia, and the United States. Most remains consist of isolated curved blades or "whorls" that are studded with teeth, that in life were situated within the midline of the upper and lower jaws. Edestus is a Greek name derived from the word edeste, in reference to the aberrant quality and size of the species' teeth. The largest species, E. heinrichi, has been conservatively estimated to reach greater than 6.7 m (22 ft) in length, around the size of the largest known great white shark, possibly making it the largest marine predator to have ever existed up to that point.

<span class="mw-page-title-main">Stethacanthidae</span> Extinct family of cartilaginous fishes

Stethacanthidae is an extinct family of prehistoric holocephalians. It is estimated to have existed approximately between 380 and 300 million years ago. Members of this family are noted for their peculiar dorsal fin.

<i>Sarcoprion</i> Extinct genus of cartilaginous fish

Sarcoprion is an extinct genus of eugeneodont holocephalan from the Permian of Greenland. Similar to other helicoprionids such as Agassizodus and Helicoprion, it possessed tooth whorls on the symphysis of the jaw as well as flattened, pavement-type teeth. It is distinguished from other members of its family by the presence of sharp, symphyseal teeth on both the upper and lower jaws. The tooth whorl on the lower jaw bore sharp, compact tooth crowns, while a row of backward facing, triangular teeth was present on the roof of the mouth. The preserved material does not show evidence of a distinct upper jaw, implying it may have been fused to the cranium, reduced, or lost entirely. The type and only species in the genus is S. edax.

<i>Campodus</i> Extinct genus of sharks

Campodus is an extinct genus of eugeneodont holocephalans from the Carboniferous. Likely one of the earliest and most basal caseodontoids, it can be characterized by its broad, ridge-ornamented crushing teeth made of various types of dentine. The type species, C. agassizianus, was originally described in 1844 based on a small number of teeth from the Namurian of Belgium.

<i>Parahelicoprion</i> Extinct genus of cartilaginous fish

Parahelicoprion is an extinct genus of shark-like cartilaginous fish that lived during the Early Permian. Two species are known ; P. clerci from Arta Beds of the Ural Mountains of Russia, and P. mariosuarezi from the Copacabana Formation of Bolivia. Members of the genus possessed a row of large tooth crowns on the midline of the lower jaw, known as a tooth whorl. The characteristics of this whorl are unique to fishes of the order Eugeneodontida, and more specifically the family Helicoprionidae to which Parahelicoprion belongs. The genus name refers to Helicoprion, another eugeneodont from the Ural Mountains that bore a similar midline tooth arrangement.

<span class="mw-page-title-main">Eugeneodontida</span> Extinct order of cartilaginous fishes

The Eugeneodontida, sometimes also called Eugeneodontiformes, is an extinct and poorly known order of cartilaginous fishes. They possessed "tooth-whorls" on the symphysis of either the lower or both jaws and pectoral fins supported by long radials. They probably lacked pelvic fins and anal fins. The palatoquadrate was either fused to the skull or reduced. Now determined to be within the Holocephali, their closest living relatives are chimaeras. The eugeneodonts are named after paleontologist Eugene S. Richardson, Jr. The group first appeared in the fossil record during the late Mississippian (Serpukhovian). The youngest eugeneodonts are known from the Early Triassic. The geologically youngest fossils of the group are known from the Sulphur Mountain Formation, Vardebukta Formation and Wordie Creek Formation (Greenland).

<span class="mw-page-title-main">Helicoprionidae</span> Family of fossil fish

Helicoprionidae is an extinct family of holocephalans within the order Eugeneodontida. Members of the Helicoprionidae possessed a "whorl" of tooth crowns connected by a single root along the midline of the lower jaw. While historically considered elasmobranchs related sharks and rays, the closest living relatives of the Helicoprionidae and all other eugeneodonts are now thought to be the ratfishes. The anatomy of the tooth-whorls vary between taxa, with some possessing highly specialized, coiling spirals, while others such as Sarcoprion and Parahelicoprion possessed shorter whorls.

<span class="mw-page-title-main">Edestidae</span> Extinct family of sharks

The Edestidae are a poorly known, extinct family of shark-like eugeneodontid holocephalid cartilaginous fish.

<span class="mw-page-title-main">Iniopterygiformes</span> Extinct order of sharks

Iniopterygiformes is an extinct order of chimaera-like cartilaginous fish that lived from the Devonian to Carboniferous periods. Fossils of them have been found in Montana, Indiana, Illinois, and Nebraska. The Iniopterygians are characterized by large pectoral fins, wing-like projections on their backs, mounted high on the body and denticulated bony plates on the head and jaws. Iniopterygian sharks were small, and their average length was about 18 inches (46 cm). The elongated pectoral fins had denticles along the leading edge which may have had a role in mating. They are thought to have been able to move their pectorals in a vertical plane, ”flying” through the water much like modern-day flying fish.

Toxoprion is an extinct genus of eugeneodont holocephalans whose fossils are found in marine strata from the Early Carboniferous until the Late Permian near Eureka, Nevada.

<i>Dracopristis</i> Extinct genus of ctenacanth

Dracopristis is an extinct genus of ctenacanth that lived during the Carboniferous period in North America, around 307 million years ago. The species was discovered in the Kinney Brick Quarry in New Mexico, US, and like many fossils from the site, is very well-preserved. A single species is known, Dracopristis hoffmanorum, which is named in honor of Ralph and Jeanette Hoffman, the owners of the quarry. Prior to being scientific named, D. hoffmanorum was informally referred to as the "Godzilla shark".

<i>Romerodus</i> Extinct genus of cartilaginous fish

Romerodus is an extinct genus of cartilaginous fish in the family Caseodontidae. While it and the rest of its family were historically considered elasmobranchs related to sharks and rays, they are now regarded as holocephalans, a diverse subclass which is today only represented by chimaeras. Romerodus is known from the Carboniferous and possibly Permian periods of North America, and the only named species, R. orodontus, was discovered in organic shale deposits in the U.S. state of Nebraska. It is one of few members of its order, the Eugeneodontida, that is known from multiple complete, well preserved body fossils, and is thus an important taxon for understanding the anatomy and ecology of less well preserved eugeneodonts such as Helicoprion. The genus name honors paleontologist Alfred Romer.

<span class="mw-page-title-main">Caseodontidae</span> Family of fossil fish

The Caseodontidae is an extinct family of eugeneodont holocephalans known from the late Paleozoic to earliest Mesozoic of Greenland, Canada and the United States. Members of the group are characterized by a reduced or absent palatoquadrate, elongate upper and mandibular rostra, and bulbous, crushing dentition, including a small symphyseal whorl of teeth on the lower jaw and batteries of teeth fused directly to the neurocranium. Several genera are known from partial or complete body fossils.

<i>Paredestus</i> Extinct genus of cartilaginous fish

Paredestus is a monotypic genus of extinct eugeneodont holocephalan from the Early Triassic of Canada. The type and only species, P. bricircum represents the last known member of the superfamily Edestoidea and among the last known eugeneodonts. It was named in 2008 based on tooth and jaw material, with the holotype representing the only known specimen.

References

  1. 1 2 3 "PBDB Taxon". The Paleobiology Database.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Zangerl, Rainer (17 March 1966). "A new shark of the family Edestidae, Ornithoprion hertwigi, from the Pennsylvanian Mecca and Logan quarry shales of Indiana". Fieldiana Geology. 16. Chicago Field Museum of Natural History: 1–42. doi: 10.5962/bhl.title.5302 . Retrieved 14 March 2020.
  3. ↑ "International Commission on Stratigraphy Subcommission on Carboniferous Stratigraphy". carboniferous.stratigraphy.org. Retrieved 2024-04-23.
  4. ↑ "Ornithoprion hertwigi". Mindat.org. Retrieved 23 April 2024.
  5. ↑ Bruner, John Clay.; Field Museum of Natural History. (1992). A catalogue of type specimens of fossil fishes in the Field Museum of Natural History / John Clay Bruner --. Chicago, Ill.: Field Museum of Natural History. p. 27. doi:10.5962/bhl.title.3361.
  6. ↑ "Ornithoprion Zangerl, 1966". www.gbif.org. Retrieved 2024-04-25.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Zangerl, Rainer (1981). Chondrichthyes 1: Paleozoic Elasmobranchii (Handbook of Paleoichthyology). Friedrich Pfell (published January 1, 1981). pp. 74–94. ISBN   978-3899370454.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 Ginter, Michał; Hampe, Oliver; Duffin, Christopher J. (2010). Handbook of paleoichthyology: teeth. München: F. Pfeil. pp. 117–120. ISBN   978-3-89937-116-1.
  9. 1 2 3 4 5 6 Zangerl, Rainer; Richardson, Eugene S. (1963). The paleoecological history of two Pennsylvanian black shales. Fieldiana. Vol. 4. Chicago: Chicago Natural History Museum. doi:10.5962/bhl.title.7199.
  10. ↑ Zangerl, Rainer (1995). "The problem of vast numbers of cladodont shark denticles in the Pennsylvanian Excello Shale of Pike County, Indiana". Journal of Paleontology. 69 (3): 556–563. Bibcode:1995JPal...69..556Z. doi:10.1017/S0022336000034922. ISSN   0022-3360.
  11. 1 2 3 4 Ellis, Richard (2003). Aquagenesis: the origin and evolution of life in the sea. New York, N.Y: Penguin. pp. 120–121. ISBN   978-0-14-200156-1.
  12. ↑ "ornitho- | Etymology of suffix ornitho-". Online Etymology Dictionary. Retrieved 17 October 2024.
  13. ↑ "prion | Etymology of prion". Online Etymology Dictionary. Retrieved 17 October 2024.
  14. 1 2 3 4 5 6 7 8 9 Ewing, Susan (2017). Resurrecting the shark: a scientific obsession and the mavericks who solved the mystery of a 270-million-year-old fossil (Ebook ed.). New York: Pegasus Books. ISBN   978-1-68177-343-8. OCLC   951925606.
  15. 1 2 3 4 Tapanila, Leif; Pruitt, Jesse; Pradel, Alan; Wilga, Cheryl D.; Ramsay, Jason B.; Schlader, Robert; Didier, Dominique A. (2013-04-23). "Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion". Biology Letters. 9 (2). doi:10.1098/rsbl.2013.0057. ISSN   1744-9561. PMC   3639784 . PMID   23445952.
  16. 1 2 3 4 5 Patterson, C. (1965-06-10). "The phylogeny of the chimaeroids". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 249 (757): 101–219. Bibcode:1965RSPTB.249..101P. doi:10.1098/rstb.1965.0010. ISSN   2054-0280.
  17. 1 2 3 4 5 6 Mutter, Raoul J.; Neuman, Andrew G. (2008-01-01). "New eugeneodontid sharks from the Lower Triassic Sulphur Mountain Formation of Western Canada". Geological Society, London, Special Publications. 295 (1): 9–41. Bibcode:2008GSLSP.295....9M. doi:10.1144/SP295.3. ISSN   0305-8719.
  18. 1 2 3 4 5 6 7 8 9 Moy-Thomas, J. A. (1971), "Subclass Chondrichthyes. Infraclass Holocephali", Palaeozoic Fishes, Boston, MA: Springer US, pp. 226–245, doi:10.1007/978-1-4684-6465-8_10, ISBN   978-1-4684-6467-2 , retrieved 2024-07-05
  19. 1 2 Troll, Ray (2002). Sharkabet: a sea of sharks from A to Z. Portland, Or: WestWinds Press. ISBN   978-1-55868-518-5.
  20. 1 2 HALL, BRIAN K. (1975). "Evolutionary Consequences of Skeletal Differentiation". American Zoologist. 15 (2): 340. doi:10.1093/icb/15.2.329. ISSN   0003-1569.
  21. 1 2 3 Poplin, Cécile M. (1978). "An Actinopterygian with a Long Rostrum from the Pennsylvanian of Logan Quarry, Indiana". Journal of Paleontology. 52 (3): 524–531. ISSN   0022-3360. JSTOR   1303953.
  22. 1 2 Ramsay, Jason B.; Wilga, Cheryl D.; Tapanila, Leif; Pruitt, Jesse; Pradel, Alan; Schlader, Robert; Didier, Dominique A. (2014-01-18). "Eating with a saw for a jaw: Functional morphology of the jaws and tooth-whorl in Helicoprion davisii". Journal of Morphology. 276 (1): 47–64. doi:10.1002/jmor.20319. ISSN   0362-2525. PMID   25181366 . Retrieved 17 April 2024.
  23. 1 2 3 Tapanila, Leif; Pruitt, Jesse; Wilga, Cheryl D.; Pradel, Alan (2018-12-26). "Saws, Scissors, and Sharks: Late Paleozoic Experimentation with Symphyseal Dentition". The Anatomical Record. 303 (2): 363–376. doi:10.1002/ar.24046. ISSN   1932-8486. PMID   30536888.
  24. 1 2 Pradel, Alan; Tafforeau, Paul; Janvier, Philippe (2010-03-04). "Study of the pectoral girdle and fins of the Late Carboniferous sibyrhynchid iniopterygians (Vertebrata, Chondrichthyes, Iniopterygia) from Kansas and Oklahoma (USA) by means of microtomography, with comments on iniopterygian relationships". Comptes Rendus Palevol. 9 (6–7): 377–387. Bibcode:2010CRPal...9..377P. doi:10.1016/j.crpv.2010.07.015. ISSN   1631-0683.
  25. ↑ PARKER, T. JEFFERY (1891-04-02). "On the Presence of a Sternum in Notidanus indicus". Nature. 43 (1118): 516. Bibcode:1891Natur..43..516P. doi:10.1038/043516b0. ISSN   0028-0836.
  26. 1 2 3 Lebedev, O. A. (2009-05-18). "A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function". Acta Zoologica. 90 (s1): 171–182. doi:10.1111/j.1463-6395.2008.00353.x. ISSN   0001-7272.
  27. ↑ Bendix-Almgreen, Svend Erik (1966). "New investigations on Helicoprion from the Phosphoria Formation of south-east Idaho, USA" (PDF). Biol. Skrifter Udgivet Af Det Kongelige Danske Videnskabernes Selskab. 14 (5): 1–54.
  28. ↑ Bendix-Almgreen, Svend Erik (1976). "Palaeovertebrate faunas of Greenland". Geology of Greenland: 557. doi:10.22008/GPUB/38226.
  29. 1 2 3 Nelson, Joseph S.; Grande, Terry; Wilson, Mark V. H. (2016). Fishes of the world (5th ed.). Hoboken, New Jersey: John Wiley & Sons. pp. 48–50. ISBN   978-1-119-22081-7.
  30. ↑ Duffin, Christopher J. (2015-10-14). "Cochliodonts and chimaeroids: Arthur Smith Woodward and the holocephalians". Geological Society, London, Special Publications. 430 (1): 137–154. doi:10.1144/sp430.9. ISSN   0305-8719.
  31. ↑ Lund, Richard; Grogan, Eileen D. (March 1997). "Relationships of the Chimaeriformes and the basal radiation of the Chondrichthyes". Reviews in Fish Biology and Fisheries. 7 (1): 65–123. Bibcode:1997RFBF....7...65L. doi:10.1023/A:1018471324332.
  32. ↑ Nielsen, Egil (1952). "On new or little known Edestidae from the Permian and Triassic of East Greenland". Meddelelser om Grønland. 144: 5–55.
  33. ↑ Ginter, Michał (2018). "The dentition of a eugeneodontiform shark from the Lower Pennsylvanian of Derbyshire, UK". Acta Palaeontologica Polonica. 63: 734. doi: 10.4202/app.00533.2018 .
  34. 1 2 Williams, Michael E. (1979). "The 'Cladodont' level sharks of the Pennsylvanian black shales of central North America". Palaeontographica: 1–15 – via ProQuest.
  35. 1 2 May, William J. (2015). "Chondrichthyans of the Excello Shale (Middle Pennsylvanian) of Rogers County, Oklahoma". Transactions of the Kansas Academy of Science. 118 (1/2): 68–74. doi:10.1660/062.118.0108. ISSN   0022-8443. JSTOR   26434035.
  36. 1 2 3 4 5 Rexroad, Carl; Wade, Jan; Merrill, Glen; Brown, Lewis; Padgett, Penny (2001). "Conodont biostratigraphy and depositional environments of the Mecca Quarry Shale Member and the Velpen Limestone Member of the Linton Formation (Pennsylvanian, Desmoinesian) in the eastern part of the Illinois Basin, U.S.A." Indiana Geological Survey (63).
  37. ↑ Philip H. Heckel (1977). "Origin of Phosphatic Black Shale Facies in Pennsylvanian Cyclothems of Mid-Continent North America". AAPG Bulletin. 61. doi:10.1306/C1EA43C4-16C9-11D7-8645000102C1865D. ISSN   0149-1423.
  38. ↑ Heckel, Philip H. (2008), "Pennsylvanian cyclothems in Midcontinent North America as far-field effects of waxing and waning of Gondwana ice sheets", Special Paper 441: Resolving the Late Paleozoic Ice Age in Time and Space, vol. 441, Geological Society of America, pp. 275–289, doi:10.1130/2008.2441(19), ISBN   978-0-8137-2441-6 , retrieved 2024-10-08
  39. ↑ Schnetz, Lisa; Butler, Richard J.; Coates, Michael I.; Sansom, Ivan J. (2024). "The skeletal completeness of the Palaeozoic chondrichthyan fossil record". Royal Society Open Science. 11 (1): 15. doi:10.1098/rsos.231451. ISSN   2054-5703. PMC   10827434 . PMID   38298400.
  40. 1 2 Itano, Wayne M. (2019-06-30). "Oriented microwear on a tooth of Edestus minor (Chondrichthyes, Eugeneodontiformes): Implications for dental function". Palaeontologia Electronica. 22 (2): 9–10. doi: 10.26879/831 . Retrieved 2024-10-06.
  41. ↑ Schultze, Hans-Peter; West, Ronald R. (1996). "An eugeneodontid elasmobranch from the Late Paleozoic of Kansas". Journal of Paleontology. 70 (1): 162–165. Bibcode:1996JPal...70..162S. doi:10.1017/S0022336000023192. ISSN   0022-3360.
  42. 1 2 3 Alexander, Richard R. (1981). "Predation Scars Preserved in Chesterian Brachiopods: Probable Culprits and Evolutionary Consequences for the Articulates". Journal of Paleontology. 55 (1): 192–203. ISSN   0022-3360. JSTOR   1304340.
  43. ↑ Taylor, Andrew (5 December 2019). "Idaho Museum of Natural History's buzzsaw sharks featured story in December National Geographic Magazine". Idaho State University News. Retrieved 25 October 2024.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.