Cretalamna | |
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Jaws and teeth of the C. hattini holotype (LACM 128126) from the Niobrara Formation of Kansas | |
Speculative skeletal reconstruction | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Lamniformes |
Family: | † Otodontidae |
Genus: | † Cretalamna Glükman, 1958 |
Type species | |
†Lamna appendiculata Agassiz, 1835 | |
Species | |
List of species
Disputed or uncertain
| |
Synonyms [1] [6] [7] [8] [9] | |
List of synonyms
|
Cretalamna is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, such as Otodus angustidens , Otodus chubutensis , and Otodus megalodon .
Cretalamna was first described by Swiss naturalist Louis Agassiz using five teeth previously identified as the common smooth-hound and collected by English paleontologist Gideon Mantell from the Southerham Grey Pit near Lewes, East Sussex. In his 1835 publication Rapport sur les poissons fossiles découverts en Angleterre, he reidentified them as a new species of porbeagle shark under the taxon Lamna appendiculata. [9] In 1843, Agassiz published Recherches sur les poissons fossiles, which reexamined Mantell's five teeth. Using them, eight additional teeth collected by Mantell, and twenty more teeth collected by various paleontologists in various locations (One tooth found by the 3rd Earl of Enniskillen from the Speeton Clay in Yorkshire; one tooth of the collection of a Strasbourg Museum from an unspecified location; one tooth of the collection of the Hancock Museum from the Marly Chalk near Cambridge; and six teeth of the collection of German paleontologist Heinrich Georg Bronn from chalk around Aachen), he described a species whose teeth had thick bulged roots, lateral cusplets, and extreme variability. Agassiz remarked that some of the examined teeth may be variable enough to belong to a separate species, but ultimately unified them under a new taxon Otodus appendiculatus. [10] The species would later be found in 1958 by Soviet paleontologist Leonid Glickman to belong to a distinct new genus- Cretalamna. [11]
Despite Agassiz's remarks on variability, [10] his ultimately broad interpretation of O. appendiculatus subsequently led the species to become a wastebasket taxon culminating to an interpretation of C. appendiculata as a variable cosmopolitan species with a 50 million year range. This changed when paleontologist Mikael Siversson found that the twenty-five syntypes actually represented a mix of at least six or more different species including three additional genera Dwardius , Cretoxyrhina , and Cretodus . To remedy the taxonomic issue, he redesignated one of the syntypes as the sole lectotype of C. appendiculata in 1999. [1] [12] In 2015, he led a study which revisited the taxonomic situation and established a renewed description of the species, which led to the erection of six additional Cretalamna species- C. catoxodon, C. deschutteri, C. ewelli, C. gertericorum, C. hattini, and C. sarcoporthea. [1]
Before Siversson, other Cretalamna species have been described. Another species described by Agassiz under the taxon Otodus latus was demoted to a variation of C. appendiculata in 1908, [13] promoted into a subspecies in 1977 by Belgian paleontologist Jaques Herman, [14] and finally elevated to the species level as Cretolamna lata by Herman and paleontologist Van Waes Hilde in 2012. [15] In 1897, French paleontologist Fernand Priem described a single tooth from the Köpinge Sandstone in Scania, Sweden under the taxon Lamna borealis. This would be revised to 'Cretolamna borealis' by Glickman in a 1980 paper. [1] In 1902, German paleontologist Johannes Wanner described teeth from Egyptian Cretaceous deposits near the Dakhla Oasis and Farafra. He noted that the teeth are almost identical with that of the Otodus appendiculatus teeth, except that the Egyptian teeth also contained two clear pairs of lateral cusplets (a feature not seen in Otodus appendiculatus). Wanner concluded that the teeth were of a closely related new species and placed it under the taxon Otodus biauriculatus. [16] In 1935, French Paleontologist Camille Arambourg described a new subspecies of C. biauriculata from teeth found in Moroccan phosphates under the taxon Lamna biauriculata maroccana, [17] which was elevated into its own species in 1997. [18] In 1972, French ichthyologist Henri Cappetta described teeth from Maastrichtian deposits near the Mentès well in Tahoua, Niger, which he assigned to the subspecies Lamna biauriculata nigeriana. [19] This subspecies would also be elevated to its own species in 1991. [20] In 1975, Cappetta and American paleontologist Gerard Case examined Cretalamna teeth described by Arambourg in 1952 from Danian deposits in Morocco and proposed that it represents a new subspecies of the type species and assigned it the taxon Cretolamna appendiculata arambourgi, [21] which Siversson et al. (2015) elevated into its own species. [1] In 2018, American paleontologists Jun Ebersole and Dana Ehret described a new species of Cretalamna from various teeth from the Eutaw Formation and Mooreville Chalk in Alabama, which they named C. bryanti. [22]
The genus Cretalamna is a portmanteau of creta, the Latin word for "chalk", prefixed to the genus Lamna , which is a romanization of the Ancient Greek λάμνα (lámna, meaning "kind of fierce shark"). When put together they mean "chalk-shark", which refers to chalk deposits from which the species' type specimens were found in. [11] The type species name appendiculata is a feminine form of the Latin word appendiculātus (having an appendage), a reference to the thick bulged roots found in C. appendiculata teeth. [10] The species name lata is derived from the feminine form of the Latin lātus (wide); a reference to the notably wide teeth of the species. [10] The species name borealis is derived from the Latin boreālis (northern); this is a reference to its discovery from fossil deposits in Sweden, a boreal locality. [1] The specific epithet of C. maroccana is a feminine form of the Latin word maroccānus (Moroccan), a reference to its type locality in Morocco. [23] C. biauriculata's specific epithet is a portmanteau derived from the Latin prefix bi- (two) prefixed onto the Latin auriculātā (eared), together meaning "having two ears". This is a reference to the species' large lateral cusplets, which somewhat resemble a pair of ears. [16] The species name nigeriana is derived from the country name Niger prefixed to the suffix -iana, a feminine variation of the Latin suffix -ānus (pertaining to), together meaning "pertaining to Niger". This is a reference to the species' type locality in Niger. [19] The species name sarcoportheta is derived from the Ancient Greek σαρκός (sarkos, meaning "flesh") prefixed to the Ancient Greek πορθητής (porthitís, meaning "destroyer"), together meaning "destroyer of flesh". The species name catoxodon is derived from the Ancient Greek κατοξυς (katoxys, meaning "very sharp") prefixed to the Ancient Greek ὀδών (odon, meaning "tooth". Together they mean "very sharp tooth", referring to the unusually sharp cutting edges of some C. catoxodon teeth. [1]
Six of the Cretalamna species have specific epithets that are named in honor of specific people, either for their contributions to the research of their associated species or for notable work they undertook. Of these six, five share a similar word structure that has a person's last name prefixed onto the Latin suffix -i (from). These species are C. arambourgi, which honors paleontologist Camille Arambourg for his discovery of the C. arambourgi type specimens and his contributions to North African paleontology; [21] C. bryanti, which honors the Bryant family who helped enhance the reputation and missions of the University of Alabama, Alabama Museum of Natural History, and McWane Science Center through their commitment to education and support; [22] C. deschutteri, which honors paleontologist Pieter De Scutter for his efforts to make Cretalamna teeth from a Bettrechies quarry available to Siversson et al. (2015) and for his work on Belgian Cenozoic sharks; C. ewelli, which honors paleontologist Keith Ewell who collected most of the C. ewelli type specimens in 2004; and C. hattini, which honors the late geologist Donald E. Hattin "for his work on the stratigraphy of the Niobrara Formation, western Kansas". The specific epithet of C. gertericorum is structured differently; it is derived from the names "Gert", "Eric", and the Latin suffix -orum (a masculine plural declension). The derived names "Gert" and "Eric" refer to fossil collectors Gert De Bie and Eric Collier, both of whom collected the majority of Cretalamna teeth examined in Siversson et al. (2015) that were from the Bettrechies quarry. [1]
The valid spelling of Cretalamna, specifically between it and 'Cretolamna', has been subject to controversy. Originally, Glickman described the genus with the intention of naming it as 'Cretolamna' , but during publication of the corresponding 1958 paper a typographical error occurred, with the print misspelling it as 'Cretalamna' . Glickman pointed out the spelling as an error and continued to use his intended spelling 'Cretolamna' in later works. [17] This spelling was universally adopted until 1999 when Siversson remarked that this violates ICZN Articles 32 and 33, reinstating 'Cretalamna' as the valid spelling. [12] Since then, the reinstatement of 'Cretalamna' gained prominence and by the 2010s, was accepted by the majority of paleontologists. [1] However, some paleontologists including Cappetta strongly opposed it. [1] [17] In an attempt to suppress the usage of 'Cretalamna' , Cappetta appealed to a representative of the ICZN, arguing that the original intentions of Glickman and the prevailing usage of 'Cretolamna' prior to Siversson (1999) secures its priority. The ICZN, who reportedly were impressed by Cappetta's "spirit", subsequently erected Article 33.3.1 of the 2000 Edition of the Code in order to address this situation in the future, [17] which states that "when an unjustified emendation is in prevailing usage and is attributed to the original author and date it is deemed to be a justified emendation". While Cappetta argued in a 2012 handbook that this new provision justifies the priority of 'Cretolamna' due to the spelling's overwhelmingly prevailing usage prior to its replacement by Siversson in 1999, Siversson himself pointed out in a 2015 paper that the provision cannot be worked retroactively, and that the continued prevailing usage of 'Cretalamna' since the provision's establishment ironically secures its priority rather than threaten it. [1] 'Cretalamna' currently remains as the most prevalent spelling and paleontologists have expressed the unlikeliness of a return to the usage of 'Cretolamna' . [17]
Cretalamna was a medium to large-sized shark. Based on vertebral comparisons with various extant lamniforms and Cretoxyrhina , a 2007 study by Kenshu Shimada estimated a total length of 2.3–3.0 metres (8–10 ft) for the most complete skeleton of a large individual (LACM 128126; C. hattini holotype [1] ). [24] Shimada previously discovered that the total length of lamniform sharks is positively correlated with the size of their teeth in a reasonably linear relationship; thus, Shimada (2007)'s estimates enabled size estimations for Cretalamna based on teeth alone. [25] [26] Subsequently, in 2019, the teeth of C. appendiculata from Himedo Park, Kugushima and Wadanohana which are larger than those in LACM 128126 yielded maximum length estimates of up to 3.4 metres (11 ft), 4.5 metres (15 ft) and 5 meters (16 ft), respectively. [26] In 2020, Shimada and colleagues estimated the maximum possible length of C. borealis up to 3.5 meters (11 ft) based on an upper jaw tooth specimen (LO 11350t) from Åsen locality. [27] [1]
The body plan of Cretalamna is almost completely known, informed by near-complete fossil impressions with soft tissue preserving the shark's outline from the Hjoula lagerstätte in Lebanon as documented by Pfiel (2021) and Greenfield (2022). [28] It was most similar to the porbeagle and salmon sharks in build, with a compact fusiform body, large pectoral and first dorsal fins and tail, and small second dorsal, pelvic, and anal fins. The first dorsal fin was positioned directly above the pectoral fins unlike its analog species, where the first dorsal fin is usually positioned behind it. [28] The tail fin was semi-lunate, [28] similar to the whale shark. [29] Such a body plan is indicative of an active fast-swimming pelagic shark likely partially warm-blooded through regional endothermy. [28] [30]
Cretalamna teeth are distinguished by a broad triangular cusp and two lateral cusplets. The cutting edges of the teeth are razor-like, while the sides have a smooth surface. Teeth symmetry is variable; some have exact bilateral symmetry whereas others have high asymmetry. Adjacent teeth do not overlap. [24]
The exact dentition of Cretalamna is uncertain due to poor fossil representation. Traditionally, most reconstructions of its dentition were constructed from individual shed teeth. [1] Based on a specimen of C. hattini (LACM 128126), the dentition of the shark follows a lamnoid pattern with at least fifteen upper tooth rows and eight lower tooth rows on each side of the jaw. The upper tooth rows contain, from front to back: two symphysial, two anterior, one intermediate, and ten lateral tooth rows. The lower tooth rows contain: two anterior, one intermediate, and five lateral tooth rows. This is given in the dental formula S2?.A2.I1.L10(+?)s?.a2.i1.l4, constructed in a 2007 study of LACM 128126 by paleontologist Kenshu Shimada. It is possible that Cretalamna contained more than two symphysial tooth rows, as the related Cretoxyrhina mantelli possessed four upper symphysial tooth rows. [24]
In C. hattini, the upper and lower jaws are similar to that of Cretoxyrhina mantelli. The jaws also resemble those of modern alopiids (thresher sharks) and lamnids. Limited fossil evidence suggests that the upper jaws extended over the lower jaws, giving Cretalamna a subterminal mouth. [24]
Cretalamna was a widespread genus found in North Africa (Morocco), the Near East (Jordan), [31] West Africa (Mali), [32] North America both on the East Coast and in the Midwest and Central America (Tonosí, Panama). [33] Deposits in Morocco are usually Eocene in age; deposits in Jordan are of Cretaceous and Eocene in age; most deposits in the U.S. are of Cretaceous and Paleocene age; [34] and deposits in Mali are of Cretaceous (Maastrichtian) age. [32] C. maroccana is more prevalent in Morocco and Jordan, while C. appendiculata is more prevalent in the United States. Both species overlapped at one point in time.
Fossil evidence of Cretalamna is found in deposits representing a diverse set of marine environments, indicating that it was able to adapt to a wide range of habitats. This may have attributed to its ability to exist through a long temporal range. [24] The fusiform body of Cretalamna suggests it was a pelagic shark. [35]
The Cretaceous waters inhabited by Cretalamna were also home to a diverse range of cartilaginous fishes, bony fishes, turtles, squamates, plesiosaurs, pterosaurs, birds, and even some non-avian dinosaurs. [24]
The tooth morphology of Cretalamna implies that it was a generalist. [24] It was a predator and preyed upon large bony fish, turtles, mosasaurs, squids, and other sharks. [36] For example, multiple teeth of C. appendiculata have been found around elasmosaurid Futabasaurus , suggesting it predated or scavenged that elasmosaur. [25] Some tooth specimens of Cretalamna exhibit heavy wear—likely the result of drastic diet changes. [1]
A possible factor to the extinction of Cretalamna is increased competition with newer generalist sharks during the Cenozoic. [24] It is widely believed that Otodus (and thus Carcharocles ) is derived from Cretalamna due to its strong similarity to certain species within the genus. [22]
The Lamniformes are an order of sharks commonly known as mackerel sharks. It includes some of the most familiar species of sharks, such as the great white as well as less familiar ones, such as the goblin shark and megamouth shark.
Carcharodon is a genus of sharks within the family Lamnidae, colloquially called the "white sharks." The only extant member is the great white shark. Extinct species include C. hubbelli and C. hastalis. The first appearance of the genus may have been as early as the Early Miocene or Late Oligocene. Carcharocles megalodon is still argued by some paleontologists to be a close relative of Carcharodon carcharias - as well as being in the same genus. When Megalodon belonged to this genus it had the scientific name Carcharodon megalodon. More recently, Megalodon has been assigned by most scientists to either the genus Carcharocles or Otodus.
Otodus megalodon, commonly known as megalodon, is an extinct species of giant mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Early Pliocene epochs. O. megalodon was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark, but has been reclassified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous.
Squalicorax, commonly known as the crow shark, is a genus of extinct lamniform shark known to have lived during the Cretaceous period. The genus had a global distribution in the Late Cretaceous epoch. Multiple species within this genus are considered to be wastebasket taxon due to morphological similarities in the teeth.
Cretoxyrhina is an extinct genus of large mackerel shark that lived about 107 to 73 million years ago during the late Albian to late Campanian of the Late Cretaceous. The type species, C. mantelli, is more commonly referred to as the Ginsu shark, first popularized in reference to the Ginsu knife, as its theoretical feeding mechanism is often compared with the "slicing and dicing" when one uses the knife. Cretoxyrhina is traditionally classified as the likely sole member of the family Cretoxyrhinidae but other taxonomic placements have been proposed, such as within the Alopiidae and Lamnidae.
Scapanorhynchus is an extinct genus of goblin shark that lived during the Cretaceous period, from the Aptian to the end of the Maastrichtian. Later records, such as those from the Miocene assigned to the species S. subulatus, are highly dubious and may be misidentified sand sharks.
Otodus is an extinct, cosmopolitan genus of mackerel shark which lived from the Paleocene to the Pliocene epoch. The name Otodus comes from Ancient Greek ὠτ- and ὀδούς – thus, "ear-shaped tooth".
Otodus angustidens is an extinct species of prehistoric megatoothed sharks in the genus Otodus, which lived during the Late Eocene and Miocene epochs about 34 to 21 million years ago. The largest individuals were about 11–12 metres (36–39 ft) long. This shark is related to another extinct megatoothed shark, the famous Otodus megalodon.
Ptychodus is a genus of extinct large durophagous (shell-crushing) lamniform sharks from the Cretaceous period, spanning from the Albian to the Campanian. Fossils of Ptychodus teeth are found in many Late Cretaceous marine sediments worldwide.
Otodus chubutensis, meaning "ear-shaped tooth of Chubut", from Ancient Greek ὠτ and ὀδούς – thus, "ear-shaped tooth", is an extinct species of prehistoric megatoothed sharks in the genus Otodus, that lived during Oligocene, Miocene, and Pliocene, in ~28–5.3 milions years ago. The largest individuals were about 13.5 metres (44 ft) long. This shark is considered a close relative of the famous prehistoric megatoothed shark O. megalodon. However, as is the case with O. megalodon, the classification of this species is disputed.
Cardabiodon is an extinct genus of large mackerel shark that lived about 95 to 91 million years ago (Ma) during the Cenomanian to Turonian of the Late Cretaceous. It is a member of the Cardabiodontidae, a family unique among mackerel sharks due to differing dental structures, and contains the two species C. ricki and C. venator. Cardabiodon fossils have been found in Australia, North America, England, and Kazakhstan. It was likely an antitropical shark that inhabited temperate neritic and offshore oceans between 40° and 60° paleolatitude, similar to the modern porbeagle shark.
Otodus auriculatus is an extinct species of large sharks in the genus Otodus of the family Otodontidae, closely related to the sharks of the genus Otodus, and also closely related to the later species megalodon. The largest individuals were about 9.5 metres (31 ft) long. Its teeth were large, having coarse serrations on the cutting edge, and also with two large cusplets. The teeth can reach up to 130 millimetres (5.1 in), and belonged to a large "megatoothed" shark.
Meristodonoides is an extinct genus of hybodont known from the mid-late Cretaceous, with potential records dating back to the Jurassic. It is one of a number of hybodont genera composed of species formerly assigned to Hybodus.
Cosmopolitodus is an extinct genus of mackerel shark that lived between thirty and one million years ago during the late Oligocene to the Early Pleistocene epochs. Its type species is Cosmopolitodus hastalis, the broad-tooth mako. In 2021, Isurus planus was reassigned to the genus, and thus became the second species C. planus. However, some researchers still consider both species of Cosmopolitodus as species of Carcharodon.
Megalolamna is an extinct genus of large mackerel shark that lived approximately 23.5 to 15 million years ago (Mya), from the Late Oligocene to the Middle Miocene epochs. Fossils belonging to this genus are known from the Americas, Europe and Japan, and have been documented in scientific literature since the late 19th century. It was in 2016 that the fossils were described as belonging to the same distinct taxon called M. paradoxodon. However, a 2024 study reveals that the taxon was already described indirectly in 1879 under the name Otodus serotinus, the only known species of this genus then being renamed as M. serotinus. It is a member of the Otodontidae, a family of large-toothed sharks known to include the contemporary megalodon.
Carcharomodus is an extinct genus of lamnid shark. Its only species is Carcharomodus escheri, commonly nicknamed the serrated mako shark or Escher's mako shark. It is an extinct lamnid that lived during the Miocene and that was formerly thought to have been transitional between the broad-toothed "mako" Cosmopolitodus hastalis and the modern great white, but is now considered to be an evolutionary dead-end with the discovery of Carcharodon hubbelli. Fossil examples have been found along northern Atlantic coastlines and in parts of Western and Central Europe.
Cretodus is an extinct genus of large mackerel sharks belonging to the proposed family Pseudoscapanorhynchidae. Cretodus lived during the Late Cretaceous, ranging from the Cenomanian to the Coniacian. The genus is well-known from strata deposited in the Western Interior Seaway, and from the Late Cretaceous of Europe, Africa, and possibly Asia. Cretodus is primarily represented in the fossil record by isolated teeth and vertebral centra, though a couple of associated dentitions and vertebral columns have been found.
Paraisurus is an extinct genus of mackerel sharks that lived during the Cretaceous. It contains four valid species, which have been found in Europe, Asia, North America, and Australia. A fifth species, P. amudarjensis, is now considered a synonym of P. compressus. While this genus is mostly known from isolated teeth, an associated dentition of P. compressus was found in the Weno Formation of Texas. It went extinct around the Albian-Cenomanian boundary, as a supposed Coniacian occurrence of "P. sp." is likely a misidentified pseudoscapanorhynchid.
Archaeolamna is an extinct genus of mackerel sharks that lived during the Cretaceous. It contains three valid species which have been found in Europe, North America, and Australia. While it is mostly known from isolated teeth, an associated set of teeth, jaws, cranial fragments, and vertebrae of A. kopingensis is known from the Pierre Shale of Kansas. Teeth of A. k. judithensis were found with a plesiosaur skeleton with bite marks from the Judith River Formation of Montana. It was a medium-sized shark with an estimated total body length of 3–4 metres (9.8–13.1 ft).
Protosqualus was a genus of dogfish shark that existed during the Cretaceous. Fossils have been found in Europe, East Asia, Antarctica, Australia, India and South America. The type species is Protosqualus sigei, which was found around an Albian aged deposit in France. There are 6 species which can be differentiated by distinct features in their teeth. Some species show some level of heterodonty, for example Protosqualus barringtonensis shows a rather high level of heterodonty within its teeth. The oldest specimens are from the Speeton Clay Formation. Protosqualus teeth are quite common in the Grey Chalk deposit of England. The genus went extinct at the end of the Cretaceous during the Cretaceous–Paleogene extinction event, with the last species in the genus being Protosqualus argentinensis from southern Argentina as well as possibly being from earlier deposits in India.