Lepidotes

Lepidotes (previously known as Lepidotus)[3] is an extinct genus of semionotid neopterygian ray-finned fish from the Jurassic period (Toarcian age) and Early Cretaceous. Fossils have been found in marine sediments of France, England, and Germany,[4] and in Early Cretaceous sediments of Brazil[5] and Bornholm, Denmark (Jydegaard Formation).[6] In 1895, many species were assigned to it by Arthur Smith Woodward. They include, L. elvensis, L. semiserratus, L. tuberculatus, L. gallineki, L. leedsi, L. latifrons, L. haydeni, L. occidentalis, L. macrocheirus, L. subovatus, L. minor, L. affinis, L. unguiculatus, L. laevis, L. maximus, L. mantelli, L. degenhardti, L. hauchecorni, L. mawsoni, L. notopterus and L.? pustulatus.[2] Numerous additional species have been assigned to it which Woodward considered indistinguishable from others.[2]

Lepidotes
Temporal range: Toarcian - Cenomanian, 180.3–94.0 Ma
Lepidotes elvensis
Fossil specimen of L. elvensis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lepisosteiformes
Genus: Lepidotes
Agassiz, 1832[1]
Type species
Lepidotes gigas
Agassiz, 1832
Speciesref name=lepidotes2012 />

L. elvensis (Blainville, 1818) (orig. Cyprinus)
L. gigas Agassiz, 1832
L. semiserratus Agassiz, 1836
L. bülowianus Jaekel, 1929

Synonyms[2]

Description

Lepidotes elvensis skull
Fossil of L. elvensis

Inhabiting both freshwater lakes and shallow seas, Lepidotes was typically about 30 centimetres (12 in) long. The body was covered with thick, enamelled scales.[7] Batteries of peg-like teeth enabled Lepidotes to crush the shells of its molluscan prey. Fossil examples of these teeth were collected in medieval times as 'toadstones', claimed to be found within the heads of toads and to have magical powers against poisoning.

Lepidotes was one of the earliest fish in which the upper jawbones were no longer attached to the jugal bone. This allowed the jaws to be stretched into a 'tube' so that the fish could suck in prey from a greater distance than in previous species.[7] This system is still seen in some modern fish, such as carp.

Lepidotes scales are ovular in shape, and are 18.5 millimetres (0.73 in) long and 3 millimetres (0.12 in) thick at the thickest point.[8] The scales are smooth and shiny on the external surface, with only a few small depressions scattered toward the centre that are shaped like punctures.[8]

Distinguishing characteristics

Many characteristics were identified by Woodward in 1895, and they are listed below:[2]

  • a fusiform trunk only moderately compressed;
  • the fact that the marginal teeth are compressed;
  • the presence of stouter inner teeth that are smooth;
  • ossified ribs;
  • very large fin-fulera on all fins;
  • that all paired fins are small;
  • short and deep dorsal and anal fins;
  • very robust, smooth or feebly oriented scales;
  • flank scales that are not much deeper than wide;
  • scales ventrally nearly as deep as broad;
  • and the presence of inconspicuous dorsal and ventral ridge-scales.

L. elvensis

L. elvensis is the type species of Lepidotes. It was described by Ducrotay de Blainville in 1818. It is known from an almost complete specimen housed in the Paris Museum of Natural History. The specimen measures up to 75 centimetres (2.46 ft) long. The specimen is from the Upper Lias, in Bavaria. The specimens P. 7406, P. 7407, P. 7408, P. 2014, P. 2054, P. 3529a, P. 3529b, 18992, 18993/94 19662, 32421, and 32422 have all been assigned to this species. The external bones of this species are smooth, but some have sparsely-placed coarse tuberculations (protuberances). The frontal bone is more than twice the length of the parietal in the specimens. It also has a comparatively narrow marginal symphysis (articulation).[2]

L. semiserratus

This species was named by Agassiz in 1837 and is known from some incomplete remains. It has been classified as closely related to L. elvensis. It is more elongate than L. elvensis, being four times as long as tall. It also has more sharply angulated sutures between its parietals, and the parietals are also proportionally longer. It is known from the specimens P. 1127, P. 7409, P. 2012, P. 2012a, P. 3527, P. 3528, P. 3528a, P. 5213, P. 5228, P. 6394, P. 7410, and 35556, all from the Upper Lias of Yorkshire.[2]

L. gallineki

L. gallineki is known from only an imperfect internal cast of the head and neck, assigned to Lepidotes by Michael (1863). The estimated length of the species is 90 centimetres (3.0 ft). The eternal bones are almost all apparently smooth. On the hinder margin, the scales are smooth and not serrated. The specimen was from the Rhaetic of Upper Silesia.[2]

L. tuberculatus

This species, named in 1837 by Louis Agassiz, is known from a single suboperculum (scale-shaped lower opercular bone). It includes an assortment of unidentified remains from Stonesfield Slate. The formation dates back to the Bathonian of England. The only certain remain that can be assigned to L. tuberculatus is the suboperculum, so all the other material is considered to be unlikely to belong to it. The specimens provisionally assigned to L. tuberculatus by Woodward are P. 471, P. 1111, P. 1111a, P. 3524, P. 7411, 28606, 28607, 30569, 37219, 47141, and 47980.[2]

L. macrocheirus

L. macrocheirus was described by Sir Philip Egerton in 1845. It could grow up to 70 centimetres (28 in) long. The trunk of the specimens are very robust, and the head measures one fifth of the total length. Like in L. elvensis, the parietals measure less than half of the frontals. The frontals are three times as long as they are wide. It possessed slightly tumid, but styliform marginal teeth. The inner teeth were large and obtuse, but there pedicles were only moderately high. The species lacked any signs of ring-vertebrae. The fin-fulcra were large, but on the medial fins they were slender. The specimens assigned to it are P. 6839, P. 6899, P. 6900, P. 7412, and P. 7413, from the Oxfordian of England.[2]

L. occidentalis

L. occidentalis is known from five ovular scales, described by Joseph Leidy in 1860.[9] The enamel surfacing of all five scales is shiny and smooth. The largest of the scales is 100 millimetres (3.9 in) long, and the smallest in 50 millimetres (2.0 in).[9]

L. haydeni

L. haydeni is a species known from a single, rectangular scale, described by Leidy in 1860. The scale is 130 millimetres (5.1 in) long and 89 millimetres (3.5 in) wide. The covering of the scale is small, rectangular squares. The root of the scale projects toward the front of one of the long sides. The specific name honors Dr. Hayden, who discovered many remains, including the only scale of L. haydeni.[9]

L. latifrons

L. latifrons was named and described by Arthur Smith Woodward in 1893. It is known from bones and scales from the head and trunk regions. It measured to about 1 metre (3.3 ft) long. The scales of this species are large and smooth. There are no traces of rings on the vertebrae. The marginal teeth are slender and styliform. The portion of the dentary that bears teeth is deepened near the symphysis. It is known from a few, mostly complete specimens, P. 6841, P. 6838, and P. 6840. The specimens date to the Oxfordian of Huntingdonshire.[2]

References

  1. ^ Agassiz, L. (1832), Untersuchungen über die fossilen Fische der Lias-Formation. Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde 3: 145
  2. ^ a b c d e f g h i j Woodward, A.S. (1895). "Catalogue of the Fossil Fishes in the British Museum (Natural History)". 2. British Museum of Natural History Department of Geology: 77–119. doi:10.5962/bhl.title.61854.
  3. ^ Hunterian Museum Geology Collections. "Lepidotes".
  4. ^ López-Arbarello, A. (2012). "Phylogenetic Interrelationships of Ginglymodian Fishes (Actinopterygii: Neopterygii)." PLoS ONE, 7(7): e39370. doi:10.1371/journal.pone.0039370
  5. ^ John G. Maisey, Discovering Fossil Fishes, 1996:150, 152.
  6. ^ Bonde, N.; Cristiansen, P. (2003). "New dinosaurs from Denmark". Comptes Rendus Palevol. 2 (13). doi:10.1016/S1631-0683(03)00009-5.
  7. ^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 37. ISBN 1-84028-152-9.
  8. ^ a b Lambe, L.M. (1902). "New Genera and Species from the Belly River Series (mid cretaceous)". Geological Survey of Canada. Contributions to Canadian Palaeontology. 3: 25–81.
  9. ^ a b c Leidy, J. (1860). "Notices of Remains of Extinct Reptiles and Fishes, Discovered by Dr. F. V. Hayden in the Bad Lands of the Judith River, Nebraska Territory". Proceedings of the Academy of Natural Sciences of Philadelphia. 8: 16. JSTOR 4059129.
1830 in paleontology

Paleontology or palaeontology (from Greek: paleo, "ancient"; ontos, "being"; and logos, "knowledge") is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1830.

Bahariya Formation

The Bahariya Formation (also transcribed as Baharija Formation) is a fossiliferous geologic formation dating back to the Early Cenomanian, which outcrops within the Bahariya depression in Egypt, and is known from oil exploration drilling across much of the Western Desert where it forms an important oil reservoir.

Callipurbeckia

Callipurbeckia is an extinct genus of neopterygian ray-finned fish from the Jurassic and Cretaceous periods. Fossils have been found in Germany, Tanzania, and England. It contains three species, which were previously classified in the related genus Lepidotes.

Crato Formation

The Crato Formation is a geologic formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly during the early Aptian age, about 113 million years ago, in a shallow inland sea. At that time, the South Atlantic was opening up in a long narrow shallow sea.

The Crato Formation earns the designation of Lagerstätte due to an exceedingly well preserved and diverse fossil faunal assemblage. Some 25 species of fossil fishes are often found with stomach contents preserved, enabling paleontologists to study predator-prey relationships in this ecosystem. There are also fine examples of pterosaurs, reptiles and amphibians, invertebrates (particularly insects), and plants. Even dinosaurs are represented: a new maniraptor was described in 1996. The unusual taphonomy of the site resulted in limestone accretions that formed nodules around dead organisms, preserving even soft parts of their anatomy.

Dromaeosauroides

Dromaeosauroides is a genus of dromaeosaurid theropod dinosaur from the Early Cretaceous of what is now Denmark. It was discovered in the Jydegaard Formation in the Robbedale valley, on the island of Bornholm in the Baltic Sea. This is the only likely place for dinosaur remains to be discovered on Danish territory, since the Mesozoic deposits exposed in the rest of the country are marine. Dromaeosauroides is the first known dinosaur from this location, and the only one which has been scientifically named. It is one of the oldest known dromaeosaurs in the world, and the first known uncontested dromaeosaur from the Early Cretaceous of Europe.

It is known from two teeth, the first of which was found in 2000 and the second in 2008. Based on the first tooth (the holotype), the genus and species Dromaeosauroides bornholmensis was named in 2003. The genus name means "Dromaeosaurus-like", due to the similarity to the teeth of that genus, and the species name means "from Bornholm". After this discovery, remains and tracks of more dinosaurs were found in several formations on Bornholm. Some teeth from the United Kingdom that have been referred to the genus Nuthetes may also belong to this animal. Coprolites containing fish remains found in the Jydegaard Formation may belong to Dromaeosauroides.

The holotype tooth is 21.7 millimetres (0.85 in) long, and the second tooth is 15 millimetres (0.59 in). They are curved and finely serrated. In life, Dromaeosauroides would have been 2 to 3 metres (7 to 10 ft) in length, and weighed about 40 kilograms (88 lb). As a dromaeosaur it would have been feathered, and had a large sickle claw on its feet like its relatives Dromaeosaurus and Deinonychus. It lived in a coastal lagoon environment with sauropods, as evidenced by a possible titanosaur tooth.

Fleming Fjord Formation

The Fleming Fjord Formation is an Upper Triassic geological formation in the northeastern coast of Jameson Land, Greenland.

It is of Norian to Rhaetian age and is subdivided into three members; at the base the Edderfugledal Member, followed by the Malmros Klint Member with the Ørsted Dal Member at the top. It was deposited in a large shallow to ephemeral lake.

Jagua Formation

The Jagua Formation is a Late Jurassic (middle to late Oxfordian) geologic formation in the Sierra de los Órganos and Sierra del Rosario mountain ranges in Pinar del Río Province, western Cuba. Plesiosaur, pliosaur, pterosaur, metriorhynchid, and turtle remains are among the fossils that have been recovered from its strata.

Jydegaard Formation

The Jydegaard Formation (also spelled as 'Jydegård') is a geological formation dating to the Early Cretaceous, about 145 to 140 million years ago. It is on the island of Bornholm, Denmark. Vertebrate fossils have been found in the formation.

Kem Kem Beds

The Kem Kem Beds (also referred to by various names including the Continental Red Beds and Continental intercalaire) is a geological formation along the border between Morocco and Algeria in southeastern Morocco, whose strata date back to the Late Cretaceous.Dinosaur remains are among the fossils that have been recovered from the formation. Recent fossil evidence in the form of isolated large abelisaurid bones and comparisons with other similarly aged deposits elsewhere in Africa indicates that the fauna of the Kem Kem Beds (specifically in regard to the numerous predatory theropod dinosaurs) may have been mixed together due to the harsh and changing geology of the region when in reality they would likely have preferred separate habitats and likely would be separated by millions of years.

List of the Mesozoic life of Montana

This list of the Mesozoic life of Montana contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Montana and are between 252.17 and 66 million years of age.

List of the prehistoric life of Montana

This list of the prehistoric life of Montana contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Montana.

Lists of prehistoric fish

Prehistoric fish are early fish that are known only from fossil records. They are the earliest known vertebrates, and include the first and extinct fish that lived through the Cambrian to the Quaternary. The study of prehistoric fish is called paleoichthyology. A few living forms, such as the coelacanth are also referred to as prehistoric fish, or even living fossils, due to their current rarity and similarity to extinct forms. Fish which have become recently extinct are not usually referred to as prehistoric fish.

Macrosemimimus

Macrosemimimus is an extinct genus of semionotiform ray-finned fish from the Late Jurassic of Germany, England and France.

National Geographic Dinosaurs

National Geographic Dinosaurs is a nonfiction reference book on dinosaurs, written by Paul Barrett, with illustrations by Raúl Martín, and an introduction by Kevin Padian. It was published in 2001 by National Geographic.

Paleobiota of the Solnhofen Formation

The Solnhofen Plattenkalk, or Solnhofen Limestone Formation, is famous for its well preserved fossil flora and fauna.

Rhododendron

Rhododendron (from Ancient Greek ῥόδον rhódon "rose" and δένδρον déndron "tree") is a genus of 1,024 species of woody plants in the heath family (Ericaceae), either evergreen or deciduous, and found mainly in Asia, although it is also widespread throughout the highlands of the Appalachian Mountains of North America. It is the national flower of Nepal as well as the state flower of West Virginia and Washington in United States, and state tree of Sikkim and Uttarakhand in India . Most species have brightly coloured flowers which bloom from late winter through to early summer.Azaleas make up two subgenera of Rhododendron. They are distinguished from "true" rhododendrons by having only five anthers per flower.

Scheenstia

Scheenstia is an extinct genus of neopterygian ray-finned fish from the Late Jurassic–Early Cretaceous periods. Fossils have been found in Bavaria, France, and England.

Scheenstia is frequently pictured as the prey of the large dinosaur Baryonyx walkeri because the scales and teeth of these fish were found in the stomach region of a fossil B. walkeri specimen. The fish remains were previously referred to the related genus Lepidotes, but all Late Jurassic–Early Cretaceous species of that genus have since been re-classified as Scheenstia following detailed phylogenetic analysis.

Semionotiformes

Semionotiformes is an order of primitive, ray-finned, primarily freshwater fish from the Triassic to the Cretaceous. The best-known genus is Semionotus of Europe and North America.

Toadstone

The toadstone, also known as bufonite (from Latin bufo, "toad"), is a mythical stone or gem that was thought to be found in the head of a toad. It was supposed to be an antidote to poison and in this it is not unlike batrachite, supposedly formed in the heads of frogs. Toadstones were actually the button-like fossilized teeth of Lepidotes, an extinct genus of ray-finned fish from the Jurassic and Cretaceous periods. They appeared to be "stones that are perfect in form" and were set by European jewellers into magical rings and amulets from Medieval times until the 18th century.

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