Xiphodolamia

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Xiphodolamia
Temporal range: Eocene
Xiphodolamia.jpg
Xiphodolamia ensis teeth from the London Clay
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Lamniformes
Family: Xiphodolamiidae
Glükman 1964 [1]
Genus: Xiphodolamia
Leidy, 1877 [2]
Species [3]
  • Xiphodolamia barbadicaCasier 1958
  • Xiphodolamia ensisLeidy 1877
  • Xiphodolamia eocaenaWoodward 1889
  • Xiphodolamia morriceiJordan and Beal 1910
  • Xiphodolamia serrataAdnet et al. 2009

Xiphodolamia is a rare extinct genus of mackerel shark which lived during the Eocene epoch. It is the only known member of the extinct family Xiphodolamiidae. [4] It is only known from isolated teeth, but has been found in Europe, Africa, and Asia. [5] It is assumed to be pelagic, occurring more frequently in deeper water deposits, most notably the London Clay and Eocene deposits in Denmark. It is distinguished by its rectangular root and twisted blade, unique among mackerel sharks. It is unclear what niche this specialized dentition helped exploit. [6]

Contents

Taxonomy and affinities

The following species have been attributed to Xiphodolamia:

X. barbadica was described from the Lutetian-aged Scotland Formation of the West Indies, and X eocaena was treated as the Ypresian-aged North American and European representative. X. ensis was originally described out of the early-middle Eocene of Central Asia and Jordan. However, X. barbadica and X. eocaeana are not easily discernable from the type species X. ensis, and most recent authors have treated them as junior synonyms. X. serrata is a serrated variety known from the Upper Eocene of Africa and Arabia. It appears to be the culmination of a singular evolving lineage, and thus Xiphodolamia is an example of anagensis. The development of serrations in Xiphodolamia mirrors that of Otodus in the Ypresian, and thus is an example of convergent evolution. This genus is not known to have survived into the Oligocene. Though in the past the genus has been placed in many orders, it is now the consensus Xiphodolamia is an unusual member of the order Lamniformes. However, its placement within Lamniformes is uncertain, especially its relationship to Lamnidae and Isurus . Some have placed it in its own family, Xiphidolamnidae. [6] It is unlikely this matter will be resolved until associated material or transitional fossils are found and described.

Paleobiogeography

Xiphodolamia is widely but thinly spread. The following places have produced Xiphodolamia teeth: [5] [6]

North America

Europe

Asia

Africa

Related Research Articles

<span class="mw-page-title-main">Lamniformes</span> Order of sharks

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.

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

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.

<i>Chlamydoselachus</i> Genus of sharks

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<i>Otodus</i> Extinct genus of sharks (fossil)

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".

<i>Carcharias</i> Genus of sharks

Carcharias is a genus of mackerel sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark.

<i>Otodus angustidens</i> Species of fossil shark

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

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.

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<i>Cosmopolitodus</i> Extinct genus of mackerel shark

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.

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

Parotodus, commonly known as the false-toothed mako shark, is an extinct genus of mackerel shark that lived approximately 53 to one million years ago during the Eocene and Pleistocene epochs. Its teeth, which are found worldwide, are often prized by fossil collectors due to their rarity. The scarcity of fossils is because Parotodus likely primarily inhabited open oceans far away from the continents. While the placement of Parotodus with the Lamniformes has been debated, most researchers agree it was probably a member of a now extinct shark clade, either a otodontid or a cardabiodont. In any case, it would have been the last members of either group. While originally being suspected of dying out at the very end of the Pliocene, fossils found in the Waccamaw Formation show that it made it to the Pleistocene.

<i>Otodus aksuaticus</i> Extinct species of shark

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

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.

<i>Abdounia</i> Extinct requiem shark

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<i>Carcharoides</i> Extinct genus of Mackerel shark

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<i>Isurolamna</i> Genus of extinct lamnid shark

Isurolamna is an extinct genus of mackerel shark from the Paleogene period. It contains at least three species and a fourth is sometimes placed in it. It is thought to be closely related to Macrorhizodus, Isurus, and Cosmopolitodus. Isurolamna arose in the Paleocene epoch during the Selandian age, and was extinct by the close of the Rupelian age of the Oligocene epoch. Some features which define this genus include a small, elliptical foramen (hole) in the middle of the lingual side of the root, triangular cusps except on lower interior teeth, and a relatively thick root with nearly vertical margins. The genus has a complicated taxonomic past.

<i>Macrorhizodus</i> Extinct genus of mackerel shark

Macrorhizodus is an extinct genus of mackerel shark which lived from the early Eocene to early Oligocene epoch of the Paleogene period. It is often considered ancestral to Isurus and sometimes considered part of it. Macrorhizodus is also likely ancestral to Cosmopolitodus. It seems to be related to Isurolamna. It is known from isolated teeth and vertebral centra as well as at least two associated dentitions. It is an incredibly widespread shark, known from every continent except Australia. This includes a report from Antarctica.

Lethenia is an extinct genus of mackerel shark from the Rupelian age of the Oligocene epoch. It is a monotypic genus, containing only L. vandenbroeki. It is considered closely related to Isurolamna and sometimes included within it. It differs in the morphology of its teeth, which are much more gracile than Isurolamna and has larger spacing between its crown and lateral cusps. Lethenia is rare and only known from isolated teeth. It is best known from the Boom Clay Formation of Belgium and the Uzunbas Formation of Kazakhstan.

Burnhamia is an extinct genus of devil ray from the Paleogene period. Due to superficial similarities, some species were originally mistaken for Cownose rays and placed in the genus Rhinoptera. It is known exclusively from dental batteries, mostly isolated teeth. There are several species attributed to this genus but their relation to each other is still unresolved. Some have proposed the type species B. daviesi arises in the late Paleocene and persists until the middle Eocene giving rise to the similar genus Eoplinthicus with an earlier offshoot leading to smaller and less ornamented species in the lower Eocene, namely B. fetahi. B. fetahi is known from Morocco and North America. B. daviesi was described from the London Clay Formation, but is well known from Eocene deposits throughout Asia, Europe, North Africa, and North America. However, teeth from the Claiborne Group of Alabama show teeth identical to B. daviesi coexisting with Eoplinthicus in the Bartonian. A Ypresian species, B. nessovi, known from a singular site in Kazakhstan was tentatively ascribed to the genus, though more material may show it warrant its own. B. crimensis is known from the Bartonian and Priabonian of Crimea.

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

Palaeocarcharias is an extinct genus of shark, known from the Jurassic of Europe. It has only a single named species, Palaeocarcharias stromeri, which is known from exceptionally preserved specimens from the Late Jurassic (Tithonian) of Germany and France. Isolated teeth of indeterminate species from England extend the range of the genus back to the Middle Jurassic (Bathonian). Morphologically, it closely resembles carpet sharks (Orectolobiformes), and is around 1 metre (3.3 ft) in total body length. However, it shares greater similarities in tooth development with mackerel sharks (Lamniformes), including the absence of orthodentine, and has been suggested to the earliest known member of the Lamniformes or a member of a sister group to the Lamniformes. A 2018 study suggested that should be classified as the sole member of the order Palaeocarchariiformes, but a subsequent 2023 study questioned this and favoured placement in Lamniformes.


Tethylamna is an extinct genus of mackerel sharks that lived during the Eocene. It contains one valid species, T. dunni, and another potential species, T. twiggsensis. Its fossils have been found in North America, South America, Africa, and Asia. T. twiggsensis has also been assigned to Brachycarcharias.

References

  1. L. S. Glükman. 1964. Class Chondrichthyes, cartilaginous fishes. Subclass Elasmobranchii (sharks). In D. V. Obruchev (ed.), Fundamentals of Paleontology. Vol. XI. Agnatha, Pisces. Izdatel'stvo "Nauka", Moscow 292-352
  2. J. Leidy. 1877. Description of vertebrate remains, chiefly from the phosphate beds of South Carolina. Journal of the Academy of Natural Sciences of Philadelphia 8:209–260
  3. "PBDB Taxon".
  4. "Xiphodolamia eocaena | Shark-References". shark-references.com. Retrieved 1 December 2024.
  5. 1 2 "elasmo.com". www.elasmo.com. Retrieved 23 August 2020.
  6. 1 2 3 Adnet, S.; Hosseinzadeh, R.; Antunes, M. T.; Balbino, A. C.; Kozlov, V. A.; Cappetta, H. (1 October 2009). "Review of the enigmatic Eocene shark genus Xiphodolamia (Chondrichthyes, Lamniformes) and description of a new species recovered from Angola, Iran and Jordan". Journal of African Earth Sciences. 55 (3): 197–204. Bibcode:2009JAfES..55..197A. doi:10.1016/j.jafrearsci.2009.04.005. ISSN   1464-343X.