Laganosuchus

Last updated • 5 min readFrom Wikipedia, The Free Encyclopedia

Laganosuchus
Temporal range: Late Cretaceous, 95  Ma
Laganosuchus.jpg
Lower jaws of L. thaumastos
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Crocodyliformes
Family: Stomatosuchidae
Genus: Laganosuchus
Sereno and Larsson, 2009 [1]
Type species
Laganosuchus thaumastos
Sereno and Larsson, 2009
Other species [2]
  • L. maghrebensisSereno and Larsson, 2009

Laganosuchus is an extinct genus of stomatosuchid crocodyliform. Fossils have been found from Niger and Morocco and date back to the Upper Cretaceous. [1] [2]

Contents

Discovery

The name means "pancake crocodile" from the Greek λαγανον, laganon ("pancake") and σοῦχος, souchos ("crocodile") in reference to the shallow depth of the skull, which is characteristic of all stomatosuchids. It has been nicknamed "PancakeCroc" by Paul Sereno and Hans Larsson, who first described the genus in a monograph published in ZooKeys in 2009 along with other Saharan crocodyliformes such as Anatosuchus and Kaprosuchus . [3]

The type species is L. thaumastos (meaning 'the astonishing pancake crocodile' from Greek θαυμαζω, thaumazo "I astonish" in reference to its unusual form) from the Cenomanian-age Echkar Formation in Niger, holotype MNN IGU13. A second species, L. maghrebensis (making a reference to the place of discovery), is known from the Kem Kem Beds in Morocco, which are also Cenomanian in age; its holotype is UCRC PV2. [4]

Description

Life restoration of L. thaumastos Laganosuchus thaumastos.jpg
Life restoration of L. thaumastos

Both species of Laganosuchus are known only from their lower jaws, those of L. thaumastos almost complete save for the left retroarticular process and those of L. maghrebensis only from a fragment of the dentary bone. L. thaumastos had a total jaw length of 838 mm and a jaw length from tip to articular facet of 750 mm, of which 490 mm actually bore teeth. Across the jaws, the total width of the lower jaw ranged from around 140 mm at the symphysis to 240 mm at the articular facets, widening fairly evenly all the way along. All the teeth were simple straight spikes, with the first pair the largest and the rest of the teeth decreasing in size towards the back of the mouth. Each side of the mouth bore 24 teeth, relatively evenly spaced save for the sixth and seventh, the dental alveoli of which have merged. Each side of these jaws is gently bowed outwards horizontally, curving more strongly towards the symphysis of the two dentary bones from the seventh alveolus forwards. The symphysis itself is relatively small and weak compared to other crocodyliforms, suggesting a very weak bite, although the bones are fully fused. The jaws are also bowed slightly, curving downwards from the articular facet and then back upwards to the symphysis of the jaws. Each of the dentary bones is very slender, only about 22 mm wide even at the slightly thickened 'chin' of the symphysis. While L. thaumastos has a small crest running along the lingual side of the dentary to thicken it, this feature is not present in L. maghrebensis. The splenial is a very thin sheet of bone in both species; it stretches much of the way along the lower jaws, but does not participate in the symphysis as the dentary does. The anterior end of the splenial differs between the two species; in L. thaumastos it is bifurcated, whereas in L. maghrebensis the anterior end of the splenial comes to a simple point. [1]

Although the posterior end of the lower jaw is not preserved in L. maghrebensis, in L. thaumastos the coronoid process is rugose, low and broad transversely, thickened by the surangular on the lingual side of the jaw, possibly signifying the attachment of powerful muscles to close the long, heavy jaws - a task that would be difficult underwater due to the large surface area between them. The external mandibular fenestra is very much reduced, forming little more than a slit. There is an unusually small adductor fossa just in front of the saddle-shaped articular facet of the glenoid; on the right side this saddle-shaped facet has irregular edges and shows some signs of bone disease, for unknown reasons. The retroarticular process is triangular in cross-section with slightly concave sides. Both the angular and the prearticular bones have thin posterior rami that entirely overlap the articular laterally and medially, leaving only the top and bottom faces of the articular open. [1]

L. thaumastos has the first two teeth in each dentary tilted forwards, and these would probably have projected out from the mouth below matching teeth in the premaxilla. Between each alveolus, the dorsal margin of the alveolar row forms a ridge that slopes downwards labially in concave depressions between the alveoli, probably indicating strongly interdigitating teeth that fitted together to form a kind of 'fish trap'. Most of the teeth are broken or missing, but a few were being replaced when the specimen died and have so been preserved in their crypts; they are straight, perfectly symmetrical spikes with no ornamentation, carinae or recurvature. In L. maghrebensis, however, the fourth tooth in the dentary is slightly larger than the first and there is no procumbency of the first dental alveoli, so its front teeth would not have projected forwards in the same fashion. [1]

Holotype dentary of L. maghrebensis Laganosuchus maghrebensis.jpg
Holotype dentary of L. maghrebensis

Both species of Laganosuchus would have been between 4–6 metres (13–20 ft) in total length, a comparatively large proportion of which would have been the large flattened head. It is possible that they had gular sacs beneath their throats, just as their relative Stomatosuchus may have done, but there is no fossil evidence either to support or disprove this theory. The jaws would have been unable to be opened or closed at speed or with much power due to their length relative to all the possible muscles that could be used to close them. [1]

Paleobiology

According to Sereno and Larsson, L. thaumastos was an approximately 6 m (20 ft) long, squat fish-eater with a 1 m (3.3 ft) flat head. [3] It would have stayed motionless for hours, waiting for prey to swim into its open jaws with spike-shaped teeth. [3] [5] These teeth would have fitted together tightly so that no fish trapped in the mouth could escape.

Related Research Articles

<span class="mw-page-title-main">Jaw</span> Opposable articulated structure at the entrance of the mouth

The jaws are a pair of opposable articulated structures at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of humans and most animals.

<i>Cristatusaurus</i> Extinct genus of dinosaurs

Cristatusaurus is a genus of theropod dinosaur that lived during the Early Cretaceous Period of what is now Niger, 112 million years ago. It was a baryonychine member of the Spinosauridae, a group of large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The type species Cristatusaurus lapparenti was named in 1998 by scientists Philippe Taquet and Dale Russell, on the basis of jaw bones and some vertebrae. Two claw fossils were also later assigned to Cristatusaurus. The animal's generic name, which means "crested reptile", alludes to a sagittal crest on top of its snout; while the specific name is in honor of the French paleontologist Albert-Félix de Lapparent. Cristatusaurus is known from the Albian to Aptian Elrhaz Formation, where it would have coexisted with sauropod and iguanodontian dinosaurs, other theropods, and various crocodylomorphs.

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

Macroplata is an extinct genus of Early Jurassic rhomaleosaurid plesiosaur which grew up to 4.65 metres (15.3 ft) in length. Like other plesiosaurs, Macroplata probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward stroke for fast swimming. Macroplata also had a relatively long neck, twice the length of the skull, in contrast to pliosaurs. It is known from a nearly complete skeleton NHMUK PV R5488 from the Blue Lias Formation (Hettangian) of Harbury, Warwickshire, UK.

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

Chimaerasuchus is an extinct genus of Chinese crocodyliform from the Early Cretaceous Wulong Formation. The four teeth in the very tip of its short snout gave it a "bucktoothed" appearance. Due its multicusped teeth and marked heterodonty, it is believed to have been an herbivore. Chimaerasuchus was originally discovered in the 1960s but not identified as a crocodyliform until 1995, instead thought to possibly be a multituberculate mammal. It is highly unusual, as only two other crocodyliforms have displayed any characteristics resembling its adaptations to herbivory.

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

Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was a fairly large predator, measuring up to 4 metres (13 ft) long.

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

Anatosuchus is an extinct genus of notosuchian crocodyliforms discovered in Gadoufaoua, Niger, and described by a team of palaeontologists led by the American Paul Sereno in 2003, in the Journal of Vertebrate Paleontology. Its duck-like snout coincidentally makes it resemble a crocoduck, an imagined hybrid animal with the head of a crocodile and the body of a duck.

<i>Razanandrongobe</i> Genus of fossil reptiles related to crocodilians

Razanandrongobe is a genus of carnivorous ziphosuchian crocodyliform from the Middle Jurassic of Madagascar. It contains the type and only species Razanandrongobe sakalavae, named in 2004 by Simone Maganuco and colleagues based on isolated bones found in 2003. The remains, which included a fragment of maxilla and teeth, originated from the Bathonian-aged Sakaraha Formation of Mahajanga, Madagascar. While they clearly belonged to a member of the Archosauria, Maganuco and colleagues refrained from assigning the genus to a specific group because the fragmentary remains resembled lineages among both the theropod dinosaurs and crocodylomorphs.

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

Volia is an extinct monospecific genus of mekosuchine crocodylian closely related to Mekosuchus and Trilophosuchus. Volia is known from a collection of largely fragmentary remains including skull bones and limbs recovered from the Voli Voli and Wainibuku Caves on Viti Levu (Fiji), with similar remains having been found on Naigani. It was around 2–3 metres (7–10 ft) long, making it the largest predatory animal on the island and subsequently most likely the apex predator of the Pleistocene ecosystems of Fiji. It may have fed on giant iguanas, flightless birds or even fish. Like its closest relatives, it may have been more terrestrial than today's crocodiles.

<i>Langstonia</i> Extinct species of reptile

Langstonia is an extinct genus of notosuchian crocodylomorph of the family Sebecidae. It lived in the middle Miocene, in the "Monkey Beds" of the Colombian Villavieja Formation. Langstonia was named in 2007 by Alfredo Paolillo and Omar Linares for fossils originally described by Langston in 1965 as Sebecus huilensis. Thus, the type species is L. huilensis.

<i>Kaprosuchus</i> Genus of crocodyliform from the Late Cretaceous period

Kaprosuchus is an extinct genus of mahajangasuchid crocodyliform. It is known from a single nearly complete skull collected from the Upper Cretaceous Echkar Formation of Niger. The name means "boar crocodile" from the Greek κάπρος, kapros ("boar") and σοῦχος, soukhos ("crocodile") in reference to its unusually large caniniform teeth which resemble those of a boar. It has been nicknamed "BoarCroc" by Paul Sereno and Hans Larsson, who first described the genus in a monograph published in ZooKeys in 2009 along with other Saharan crocodyliformes such as Anatosuchus and Laganosuchus. The type species is K. saharicus.

<span class="mw-page-title-main">Stomatosuchidae</span> Extinct family of reptiles

Stomatosuchidae is an extinct family of neosuchian crocodylomorphs. It is defined as the most inclusive clade containing Stomatosuchus inermis but not Notosuchus terrestris, Simosuchus clarki, Araripesuchus gomesii, Baurusuchus pachecoi, Peirosaurus torminni, or Crocodylus niloticus. Two genera are known to belong to Stomatosuchidae: Stomatosuchus, the type genus, and Laganosuchus. Fossils have been found from Egypt, Morocco, and Niger. Both lived during the Cenomanian stage of the Late Cretaceous. The skulls of stomatosuchids are said to be platyrostral because they have unusually flattened, elongate, duck-shaped craniums with U-shaped jaws. This platyrostral condition is similar to what is seen in the "nettosuchid" Mourasuchus, which is not closely related to stomatosuchids as it is a more derived alligatoroid that existed during the Miocene.

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

Sebecus is an extinct genus of sebecid crocodylomorph from Eocene of South America. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by two species, the type S. icaeorhinus and S. ayrampu. Several other species have been referred to Sebecus, but were later reclassified as their own genera.

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

Platyognathus is an extinct genus of protosuchian crocodyliform. Fossils are known from the Early Jurassic Lower Lufeng Formation in Yunnan, China and belong to the type and only species, P. hsui.

<span class="mw-page-title-main">Mandible</span> Lower jaw bone

In jawed vertebrates, the mandible, lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth.

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

Astorgosuchus is an extinct monospecific genus of crocodilian, closely related to true crocodiles, that lived in Pakistan during the late Oligocene period. This crocodile may have reached lengths of up to 7–8 m (23–26 ft) and is known to have preyed on many of the large mammals found in its environment. Bite marks of a large crocodile have been found on the bones of juvenile Paraceratherium, however if these were left by Astorgosuchus cannot be said with certainty. The genus contains a single species, Astorgosuchus bugtiensis, which was originally named as a species of Crocodylus in 1908 and was moved to its own genus in 2019.

<i>Manubrantlia</i> Extinct genus of temnospondyls

Manubrantlia was a genus of lapillopsid temnospondyls from the Early Triassic Panchet Formation of India. This genus is only known from a single holotype left jaw, given the designation ISI A 57. Despite the paucity of remains, the jaw is still identifiable as belonging to a relative of Lapillopsis. For example, all three of its coronoid bones possessed teeth, the articular bone is partially visible in lateral (outer) view, and its postsplenial does not contact the posterior meckelian foramen. However, the jaw also possesses certain unique features which justify the erection of a new genus separate from Lapillopsis. For example, the mandible is twice the size of any jaws referred to other lapillopsids. The most notable unique feature is an enlarged "pump-handle" shaped arcadian process at the back of the jaw. This structure is responsible for the generic name of this genus, as "Manubrantlia" translates from Latin to the English expression "pump-handle". The type and only known species of this genus is Manubrantlia khaki. The specific name refers to the greenish-brown mudstones of the Panchet Formation, with a color that had been described as "khaki" by the first British geologists who studied the formation.

Sabinosuchus is a genus of Mesoeucrocodylian, from the Maastrichtian Escondido Formation of Coahuila, Mexico, with Sabinosuchus coahuilensis as the type species. First described as a putative dyrosaurid by Shiller II et al. (2016), it was later recovered as a pholidosaurid by Jouve & Jalil (2020).

<i>Kansaignathus</i> Extinct genus of dinosaurs

Kansaignathus is an extinct genus of dromaeosaurid theropod from the Late Cretaceous Yalovach Formation of Tajikistan. The genus contains only one species, the type species, K. sogdianus. The generic name of Kansaignathus comes from near the town of Konsoy where it was discovered and the Greek word "gnathos" meaning "jaw". The specific epithet "sogdianus" is derived from the historical region of Sogdiana, which was an ancient name for the Fergana Valley region where the fossil was discovered. Kansaignathus is known from a single right dentary bone and a few post-cranial bone fragments. It was the first, and so far the only, dinosaur from Tajikistan to be described and named.

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

Taytalura is an extinct genus of lepidosauromorph reptile from the Late Triassic of Argentina. It contains a single species, Taytalura alcoberi, which is based on a well-preserved skull from the fossiliferous Ischigualasto Formation. As a lepidosauromorph, Taytalura is a distant relative of modern lepidosaurs such as sphenodontians and squamates. Taytalura did not belong to any group of modern lepidosaurs, since it bears unique features, such as unfused bones in the skull roof and teeth which all sit loosely in a deep groove without sockets. Regardless, Micro-CT scanning reveals features of the skull previously only seen in rhynchocephalians. This suggests that the ancestral condition of the skull in lepidosaurs was more similar to sphenodonts than to squamates.

Eurycephalosuchus is an extinct genus of orientalosuchine alligatoroid from the Late Cretaceous Jiangxi Province of China. Known from a well preserved skull and mandible alongside various postcranial remains, Eurycephalosuchus possessed a short and broad skull with a very short skulltable. Eurycephalosuchus lived with at least one other crocodilian, an indetermined member of the clade Brevirostres. The genus is monotypic, containing only the species Eurycephalosuchus gannanensis.

References

  1. 1 2 3 4 5 6 Sereno, Paul; Larsson, Hans (2009-11-19). "Cretaceous Crocodyliforms from the Sahara". ZooKeys (28): 1–143. doi: 10.3897/zookeys.28.325 . ISSN   1313-2970.
  2. 1 2 "†Laganosuchus Sereno and Larsson 2009". Paleobiology Database. Fossilworks. Retrieved 17 December 2021.
  3. 1 2 3 Schmid, Randolph E. (19 November 2009). "3 new ancient crocodile species fossils found". The Associated Press. Archived from the original on November 27, 2009.
  4. Sereno, P. C.; Dutheil, D. B.; Iarochene, M.; Larsson, H. C. E.; Lyon, G. H.; Magwene, P. M.; Sidor, C. A.; Varricchio, D. J.; Wilson, J. A. (1996). "Predatory dinosaurs from the Sahara and Late Cretaceous faunal differentiation" (PDF). Science. 272 (5264): 986–991. Bibcode:1996Sci...272..986S. doi:10.1126/science.272.5264.986. PMID   8662584. S2CID   39658297.
  5. Devlin, Hannah (20 November 2009). "Meet Boar, Rat and Pancake: the ancient, giant crocodiles found in Sahara". Times Online.