Osteolaeminae

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Osteolaeminae
Temporal range: EoceneHolocene, 38–0  Ma
West African Dwarf Crocodile 5.jpg
West African dwarf crocodile (Osteolaemus tetraspis)
Mecistops leptorhynchus 2009.jpg
Central African slender-snouted crocodile (Mecistops leptorhynchus)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Crocodilia
Family: Crocodylidae
Subfamily: Osteolaeminae
Brochu, 2003
Genera

Osteolaeminae is a subfamily of true crocodiles within the family Crocodylidae containing the dwarf crocodiles and slender-snouted crocodiles, and is the sister taxon to Crocodylinae.

Contents

Taxonomy

Osteolaeminae was named by Christopher Brochu in 2003 as a subfamily of Crocodylidae separate from Crocodylinae, and is cladistically defined as Osteolaemus tetraspis (the Dwarf crocodile) and all crocodylians more closely related to it than to Crocodylus niloticus (the Nile crocodile). [2] [3] This is a stem-based definition, and is the sister taxon to Crocodylinae. Osteolaeminae contains the two extant genera Osteolaemus and Mecistops , along with several extinct genera, although the number of extant species within Osteolaeminae is currently in question. [4]

Phylogeny

The cladogram below is based on two studies that combined morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data. [5] [6]

Crocodylidae
Osteolaeminae

Mecistops cataphractus West African slender-snouted crocodile

Euthecodon

Brochuchus

Rimasuchus

Osteolaemus osborni Osborn’s dwarf crocodile

Osteolaemus tetraspis Dwarf crocodile

Crocodylinae

Voay

Crocodylus

Crocodylus anthropophagus

Crocodylus thorbjarnarsoni

Crocodylus palaeindicus

Crocodylus Tirari Desert

Crocodylus johnstoni Freshwater crocodile

Crocodylus novaeguineae New Guinea crocodile

Crocodylus mindorensis Philippine crocodile

Crocodylus porosus Saltwater crocodile

Crocodylus siamensis Siamese crocodile

Crocodylus palustris Mugger crocodile

Crocodylus checchiai

Crocodylus falconensis

Crocodylus suchus West African crocodile

Crocodylus niloticus Nile crocodile

Crocodylus moreletii Morelet's crocodile

Crocodylus rhombifer Cuban crocodile

Crocodylus intermedius Orinoco crocodile

Crocodylus acutus American crocodile

(crown group)

Alternatively, other morphological studies have recovered Mecistops as a basal member of Crocodylinae, more closely related to Crocodylus than to Osteolaemus and the other members of Osteolaeminae, [3] [7] as shown in the cladogram below. [7]

Crocodylidae
Osteolaeminae

Rimasuchus lloydi

Voay robustus

Osteolaemus osborni Osborn’s dwarf crocodile

Osteolaemus tetraspis Dwarf crocodile

"Crocodylus" gariepensis

Brochuchus parvidens

Brochuchus pigotti

Euthecodon arambourgi

Euthecodon brumpti

Crocodylinae

Mecistops cataphractus West African slender-snouted crocodile

Crocodylus thorbjarnarsoni

Crocodylus anthropophagus

Crocodylus niloticus Nile crocodile

Crocodylus checchiai

Crocodylus moreletii Morelet's crocodile

Crocodylus intermedius Orinoco crocodile

Crocodylus acutus American crocodile

Crocodylus rhombifer Cuban crocodile

Crocodylus palaeindicus

Crocodylus palustris Mugger crocodile

Crocodylus ossifragus

Crocodylus siamensis Siamese crocodile

Crocodylus mindorensis Philippine crocodile

Crocodylus johnstoni Freshwater crocodile

Crocodylus porosus Saltwater crocodile

Crocodylus raninus Borneo crocodile

Crocodylus novaeguineae New Guinea crocodile  

Paleoafrican Crocodylus
Neotropical Crocodylus
Indo-Pacific Crocodylus

Species list

Related Research Articles

<span class="mw-page-title-main">Crocodile</span> Family of large reptilian carnivores

Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial among other extinct taxa.

<span class="mw-page-title-main">Crocodylinae</span> Subfamily of crocodiles

Crocodylinae is a subfamily of true crocodiles within the family Crocodylidae, and is the sister taxon to Osteolaeminae.

<span class="mw-page-title-main">Gavialinae</span> Subfamily of gharial crocodylians

Gavialinae is a subfamily of large semiaquatic crocodilian reptiles, resembling crocodiles, but with much thinner snouts. Gavialinae is one of the two major subfamilies within the family Gavialidae - the other being the subfamily Tomistominae, which contains the false gharial and extinct relatives.

<i>Crocodylus</i> Genus of reptiles

Crocodylus is a genus of true crocodiles in the family Crocodylidae.

<span class="mw-page-title-main">Dwarf crocodile</span> Species of reptile

The dwarf crocodile, also known as the African dwarf crocodile, broad-snouted crocodile or bony crocodile, is an African crocodile that is also the smallest extant (living) species of crocodile.

<i>Mecistops</i> Genus of reptiles

Mecistops is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa.

Aldabrachampsus is an extinct genus of small horned crocodile known from fragmentary remains. It lived during the Pleistocene on Aldabra Atoll, Seychelles in the western Indian Ocean. The name Aldabrachampsus dilophus means "Two-crested crocodile from Aldabra". It was a small animal, reaching a length of 2–2.5 m, comparable in size to the smallest extant crocodilians.

<i>Euthecodon</i> Extinct genus of crocodilian

Euthecodon is an extinct genus of long-snouted crocodile. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya, Ethiopia, and Libya. Although superficially resembling that of gharials, the long snout was a trait developed independently from that of other crocodilians and suggests a diet of primarily fish. Euthecodon coexisted with a wide range of other crocodiles in the areas it inhabited before eventually going extinct during the Pleistocene.

<i>Voay</i> Extinct genus of reptiles

Voay is an extinct genus of crocodile from Madagascar that lived during the Late Pleistocene to Holocene, containing only one species, V. robustus. Numerous subfossils have been found, including complete skulls, noted for their distinctive pair of horns on the posterior, as well as vertebrae and osteoderms from such places as Ambolisatra and Antsirabe. The genus is thought to have become extinct relatively recently. It has been suggested to have disappeared in the extinction event that wiped out much of the endemic megafauna on Madagascar, such as the elephant bird and Malagasy hippo, following the arrival of humans to Madagascar around 2000 years ago. Its name comes from the Malagasy word for crocodile.

<i>Kentisuchus</i> Extinct genus of reptiles

Kentisuchus is an extinct genus of gavialoid crocodylian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found from England and France that date back to the early Eocene. The genus has also been recorded from Ukraine, but it unclear whether specimens from Ukraine are referable to Kentisuchus.

<span class="mw-page-title-main">Crocodyloidea</span> Superfamily of crocodiles

Crocodyloidea is one of three superfamilies of crocodilians, the other two being Alligatoroidea and Gavialoidea, and it includes the crocodiles. Crocodyloidea may also include the extinct Mekosuchinae, native to Australasia from the Eocene to the Holocene, although this is disputed.

Rimasuchus is an extinct genus of crocodile from the Miocene of Egypt and possibly Libya. Only one species - Rimasuchus lloydi - is currently known. It was previously thought to be a species of Crocodylus, but is now thought to be more closely related to the modern African dwarf crocodiles (Osteolaemus).

<span class="mw-page-title-main">Brevirostres</span> Taxon of reptiles

Brevirostres is a paraphyletic group of crocodilians that included alligatoroids and crocodyloids. Brevirostres are crocodilians with small snouts, and are distinguished from the long-snouted gharials. It is defined phylogenetically as the last common ancestor of Alligator mississippiensis and Crocodylus niloticus and all of its descendants. This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species, and placed the gharials outside the group due to their unique skull structure, and can be shown in the simplified cladogram below:

<i>"Crocodylus" affinis</i> Species of reptile (fossil)

"Crocodylus" affinis is an extinct species of crocodyloid from the Eocene of Wyoming. Fossils were first described from the Bridger Formation by American paleontologist Othniel Charles Marsh in 1871. Marsh described the species, along with every other species of crocodyloid in the Bridger Formation, under the genus Crocodylus. The known specimen of "Crocodylus" affinis is a skull found at Grizzly Buttes, Wyoming, measuring 13 inches in length on the upper surface. Recent phylogenetic studies of crocodyloids show that "C." affinis is not a species of Crocodylus, but a genus has not yet been erected to include the species. Other Bridger species such as Crocodylus clavis and Brachyuranochampsa zangerli have been synonymized with "C." affinis.

<i>"Crocodylus" acer</i> Extinct species of reptile

"Crocodylus" acer is an extinct species of crocodyloid from the Eocene of Utah. A single well preserved skull was described by paleontologist Edward Drinker Cope in 1882 and remains the only known fossil of the species. It was found from the Wasatchian-age Green River Formation. "C." acer had a long, narrow snout and a low, flattened skull.

"Crocodylus" megarhinus is an extinct species of crocodile from the Eocene of Egypt. A partial skull was found by British paleontologist Charles William Andrews in the Fayum Depression. Andrews named Crocodylus megarhinus in 1905 on the basis of the holotype skull. A complete skull was also uncovered from Egypt in 1907 but was not recognized as "C." megarhinus until 1927.

Crocodylus palaeindicus is an extinct species of crocodile from southern Asia. C. palaeindicus lived from the Miocene to the Pliocene. It may be an ancestor of the living Mugger crocodile.

Brochuchus is an extinct genus of crocodile known from the Early Miocene Hiwegi Formation of Rusinga Island in Lake Victoria, Kenya; it was originally named as a species of Crocodylus. It contains two species, B. parvidens and B. pigotti. Brochuchus belongs to the family Crocodylidae, which includes all living crocodiles. The closest living relative of Brochuchus is Osteolaemus, the dwarf crocodile. Compared to Osteolaemus, which has a small body and blunt snout, Brochuchus has a more generalized crocodylid anatomy. Brochuchus is characterized by a flat and relatively narrow skull, and although it is larger than Osteolaemus it is smaller than most other crocodylids. It has two prominent bumps on the surface of its snout.

<i>Kinyang</i> (genus) Extinct genus of reptiles

Kinyang is an extinct genus of osteolaemine crocodile from the Early to Middle Miocene of Kenya. Two species are currently known, K. mabokoensis from the Lake Victoria basin and K. tchernovi from the Lake Victoria and Lake Turkana basin. Kinyang had an exceptionally broad and robust skull, much wider than that of any living crocodile species. This might have allowed it to attack and kill prey its own size or even bigger. Kinyang is notably larger than its contemporary relative Brochuchus. While the precise reasons for the extinction of Kinyang are not known, it coincides with a larger faunal turnover that saw osteolaemines replaced by the still dominant crocodylines. One reason for this shift may have been the drying climate of Africa at the time, which caused rainforests to be replaced by more open environments and disrupted the nesting behavior of osteolaemines due to their dependence on foliage.

References

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  2. Brochu, C. A.; Storrs, G. W. (2012). "A giant crocodile from the Plio-Pleistocene of Kenya, the phylogenetic relationships of Neogene African crocodylines, and the antiquity of Crocodylus in Africa". Journal of Vertebrate Paleontology. 32 (3): 587–602. doi:10.1080/02724634.2012.652324. S2CID   85103427.
  3. 1 2 Rio, Jonathan P.; Mannion, Philip D. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ . 9: e12094. doi: 10.7717/peerj.12094 . PMC   8428266 . PMID   34567843.
  4. 1 2 Eaton, Mitchell J.; Andrew Martin; John Thorbjarnarson; George Amato (March 2009). "Species-level diversification of African dwarf crocodiles (Genus Osteolaemus): A geographic and phylogenetic perspective". Molecular Phylogenetics and Evolution. 50 (3): 496–506. doi:10.1016/j.ympev.2008.11.009. PMID   19056500.
  5. Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B . 285 (1881). doi: 10.1098/rspb.2018.1071 . PMC   6030529 . PMID   30051855.
  6. Hekkala, E.; Gatesy, J.; Narechania, A.; Meredith, R.; Russello, M.; Aardema, M. L.; Jensen, E.; Montanari, S.; Brochu, C.; Norell, M.; Amato, G. (2021-04-27). "Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, Voay robustus". Communications Biology. 4 (1): 505. doi: 10.1038/s42003-021-02017-0 . ISSN   2399-3642. PMC   8079395 . PMID   33907305.
  7. 1 2 Azarra, Beatrice; Boschian, Giovanni; Brochu, Christopher; Delfino, Massimo; Iurino, Dawid Adam; Kimambo, Jackson Stanley; Manzi, Giorgio; Masao, Fidelis T.; Menconero, Sofia; Njau, Jackson K; Cherin, Marco (2021). "A new cranium of Crocodylus anthropophagus from Olduvai Gorge, northern Tanzania". Rivista Italiana di Paleontologia e Stratigrafia (Research in Paleontology and Stratigraphy). 127 (2): 275–295. doi:10.13130/2039-4942/15771.