Ocepechelon

Last updated

Ocepechelon
Temporal range: Maastrichtian
~67  Ma
O
S
D
C
P
T
J
K
Pg
N
Ocepechelon bouyai skull lat.png
Skull and size comparison of Ocepechelon
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Clade: Panchelonioidea (?)
Family: Protostegidae
Genus: Ocepechelon
Bardet et al, 2013
Type species
Ocepechelon bouyai
Bardet et al, 2013

Ocepechelon is an extinct genus of giant protostegid sea turtle known from Late Cretaceous (late Maastrichtian stage, 67 Myr) phosphatic deposits of the Oulad Abdoun Basin, Khouribga Province of Morocco. It is known from the holotype OCP DEK/GE 516, a complete but isolated 70-cm-long skull, making it one of the largest marine turtles ever described. It was first named by Nathalie Bardet, Nour-Eddine Jalil, France de Lapparent de Broin, Damien Germain, Olivier Lambert and Mbarek Amaghzaz in 2013, and the type species is Ocepechelon bouyai. The feeding apparatus of Ocepechelon, a bony pipette-like snout, is unique among tetrapods and shares unique convergences with both syngnathid fishes (unique long tubular bony snout ending in a rounded and forward directed mouth) and beaked whales (large size and elongated edentulous jaws). [1]

Contents

Suction feeding by an Ocepechelon (animation)

Description

Ocepechelon is known solely from an isolated yet complete skull, 70 centimetres (28 in) in length. From the size of the skull, it must have been one of the largest turtles that ever lived, with estimated carapace length of 130–150 centimetres (4.3–4.9 ft) and total length of 240 centimetres (7.9 ft). [1] The skull of this genus was not only exceptional in size, but also in appearance: large at the back, it narrowed at the front to form a sort of elongated, narrow, bony funnel. [1] The lower jaw and hyoid remain unknown.

The skull roof of Ocepechelon is dorsoventrally compressed, with a wide cerebral cavity and a lateral wall of the cranial cavity that is bowed anteromedially. [1] Its longirostrine snout has been compared to a pipette, and is unique among all tetrapods. Its flattened, streamlined skull, as well as the dorsal position of its orbits and nares, suggest it was a seagoing species which hunted close to the water's surface. This hypothesis is supported by sedimentological analysis and its skull anatomy. Several aspects of Ocepechelon's skull anatomy suggest it may have been a suction feeder, namely the tube-like upper jaw. In general, the skull must have looked something like a toothless crocodile: there were no teeth, but the eyes were upturned, as were the nostrils, which were set far back. It is the only tetrapod to have developed an evolutionary convergence with both syngnathid fishes and beaked whales, since it possessed a large head but a long, narrow, toothless snout. [1]

Like other genera in the Panchelonioidea, it likely possessed flippers, allowing an active swimming lifestyle. Material potentially referable to Ocepechelon supports this hypothesis. [1]

Phylogeny

Due to the limited fossil material available, Bardet et al. (2013) used numerous methods to assess the phylogenetic position of the animal. The removal of outgroup taxa, except for the hypothetical taxon, deliberated some relationships and showed that Ocepechelon and Bouliachelys could be basal dermochelyoids, forming a polytomy with the Dermochelyidae and Protostegidae. The inclusion of Chelomacryptodira resolved this polytomy, and suggested that Ocepechelon was the most basal dermochelyid known. [1]

Below is a cladogram from the description of Ocepechelon, by Bardet et al. (2013).

Protostegidae

Calcarichelys

Syllomus

Ocepechelon

Alienochelys

Protostega

Archelon

Chelosphargis

Desmatochelys lowi

Bouliachelys

Santanachelys

Desmatochelys padillaii


However, Scavezzoni & Fischer (2018), [2] in their phylogenetic analysis, showed that Dermatochelyidae and Protostegidae did not form a clade, and classified Ocepechelon within Protostegidae, as a sister taxon to Alienochelys. Below is a subsequent phylogeny based on Scavezzoni & Fischer's cladogram and Evers et al. (2019) [3] who both recovered it as a protostegid.


  Panchelonioidea  

Toxochelys

 Protostegidae  

Desmatochelys

Ocepechelon

Archelon

Protostega

Calcarichelys

Bouliachelys

Chelosphargis

Santanachelys

Notochelone

Rhinochelys

  Chelonioidea  

Corsochelys

Dermochelyidae

Nichollsemys

Allopleuron

Cheloniidae

Argillochelys

Procolpochelys

Eochelone

Puppigerus

Ctenochelys

Peritresius

Cabindachelys

Paleobiology

Life restoration of Ocepechelon bouyai. Ocepechelon bouyai reconstruction.png
Life restoration of Ocepechelon bouyai.

The remarkable similarities between Ocepechelon and beaked whales (as well as syngnathid fishes) have led paleontologists to speculate about Ocepechelon's possible mode of feeding. Since both beaked whales and syngnathids are organisms that feed by sucking (i.e., creating a vacuum to suck in small prey), paleontologists believe that Ocepechelon may have also fed in this way. [1] This animal probably swam near the surface of the warm waters it inhabited, swallowing large quantities of small fish, cephalopods and jellyfish. Based on comparisons with other present-day turtles, it is also speculated that Ocepechelon may have been equipped with small spiny structures within its throat. These papillae are currently present in the leatherback sea turtle (one of Ocepechelon's closest relatives), and not only filter water, but also create a sharp barrier to prey attempting to escape. Ocepechelon may have had a similar structure, as well as other papillae along the edges of the mouth. [1]

Related Research Articles

<span class="mw-page-title-main">Nasal bone</span> Two bones in the bridge of the human nose

The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose.

<i>Archelon</i> Cretaceous marine turtle and the largest turtle ever discovered

Archelon is an extinct marine turtle from the Late Cretaceous, and is the largest turtle ever to have been documented, with the biggest specimen measuring 4.6 m (15 ft) from head to tail and 2.2–3.2 t in body mass. It is known only from the Pierre Shale and has one species, A. ischyros. In the past, the genus also contained A. marshii and A. copei, though these have been reassigned to Protostega and Kansastega, respectively. The genus was named in 1895 by American paleontologist George Reber Wieland based on a skeleton from South Dakota, who placed it into the extinct family Protostegidae. The leatherback sea turtle was once thought to be its closest living relative, but now, Protostegidae is thought to be a completely separate lineage from any living sea turtle.

<span class="mw-page-title-main">Flipper (anatomy)</span> Flattened limb adapted for propulsion and maneuvering in water

A flipper is a broad, flattened limb adapted for aquatic locomotion. It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish.

<i>Gastonia</i> (dinosaur) Ankylosaurian dinosaur genus from the Early Cretaceous period

Gastonia is a genus of herbivorous ankylosaurian dinosaur from the Early Cretaceous of North America, around 139 to 134.6 million years ago. It is often considered a nodosaurid closely related to Polacanthus. Gastonia has a sacral shield and large shoulder spikes.

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

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.

<span class="mw-page-title-main">Protostegidae</span> Extinct family of turtles

Protostegidae is a family of extinct marine turtles that lived during the Cretaceous period. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head one metre (39 in) long. Like most sea turtles, they had flattened bodies and flippers for front appendages; protostegids had minimal shells like leatherback turtles of modern times.

<i>Bouliachelys</i> Extinct genus of turtles

Bouliachelys is an extinct genus of sea turtle from Cretaceous Australia. It was originally described as a member of Protostegidae. In 2013 study it was considered to be a member of Dermochelyoidae, although later studies consider it as a protostegid again.

<i>Spathicephalus</i> Extinct genus of tetrapods

Spathicephalus is an extinct genus of stem tetrapods that lived during the middle of the Carboniferous Period. The genus includes two species: the type species S. mirus from Scotland, which is known from two mostly complete skulls and other cranial material, and the species S. pereger from Nova Scotia, which is known from a single fragment of the skull table. Based on the S. mirus material, the appearance of Spathicephalus is unlike that of any other early tetrapod, with a flattened, square-shaped skull and jaws lined with hundreds of very small chisel-like teeth. However, Spathicephalus shares several anatomical features with a family of stem tetrapods called Baphetidae, leading most paleontologists who have studied the genus to place it within a larger group called Baphetoidea, often as part of its own monotypic family Spathicephalidae. Spathicephalus is thought to have fed on aquatic invertebrates through a combination of suction feeding and filter feeding.

<span class="mw-page-title-main">Skull roof</span> Roofing bones of the skull

The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium.

<i>Acamptonectes</i> Extinct genus of ophthalmosaurid ichthyosaur known from England and Germany

Acamptonectes is a genus of ophthalmosaurid ichthyosaurs, a type of dolphin-like marine reptiles, that lived during the Early Cretaceous around 130 million years ago. The first specimen, a partial adult skeleton, was discovered in Speeton, England, in 1958, but was not formally described until 2012 by Valentin Fischer and colleagues. They also recognised a partial subadult skeleton belonging to the genus from Cremlingen, Germany, and specimens from other localities in England. The genus contains the single species Acamptonectes densus; the generic name means "rigid swimmer" and the specific name means "compact" or "tightly packed".

<i>Caupedactylus</i> Genus of tapejarid pterosaur form the Early Cretaceous

Caupedactylus is an extinct genus of tapejarid azhdarchoid pterosaur known from the Early Cretaceous period of what is now the Romualdo Formation of the Araripe Basin in northeastern Brazil. The type and only species of Caupedactylus is Caupedactylus ybaka.

<i>Entelognathus</i> Placoderm fish from the late Ludlow epoch of the Silurian period

Entelognathus primordialis is an early placoderm from the late Silurian of Qujing, Yunnan, 419 million years ago.

<i>Ocepeia</i> Extinct Afrotherian mammal

Ocepeia is an extinct genus of afrotherian mammal that lived in present-day Morocco during the middle Paleocene epoch, approximately 60 million years ago. First named and described in 2001, the type species is O. daouiensis from the Selandian stage of Morocco's Ouled Abdoun Basin. A second, larger species, O. grandis, is known from the Thanetian, a slightly younger stage in the same area. In life, the two species are estimated to have weighed about 3.5 kg (7.7 lb) and 10 kg (22 lb), respectively, and are believed to have been specialized leaf-eaters. The fossil skulls of Ocepeia are the oldest known afrotherian skulls, and the best-known of any Paleocene mammal in Africa.

<span class="mw-page-title-main">Ouled Abdoun Basin</span> Phosphate basin in Morocco

The Oulad Abdoun Basin is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and at least 26.8 billion tons of phosphate. It is also known as an important site for vertebrate fossils, with deposits ranging from the Late Cretaceous (Cenomanian-Turonian) to the Eocene epoch (Ypresian), a period of about 25 million years.

<i>Rhinochelys</i> Extinct genus of turtles

Rhinochelys is an extinct genus of sea turtles belonging to the family Protostegidae.

<i>Alienochelys</i> Extinct genus of turtles

Alienochelys is an extinct genus of sea turtle known from Maastrichian-aged Cretaceous phosphates in Morocco. With a skull measuring 41.5 centimetres (1.36 ft) long, it would have been a very large turtle. It was first described as a member of the family Dermochelyidae, meaning that it is a relative of the modern leatherback turtle, though a 2018 study identifies it as a sister taxon of Ocepechelon belonging to the family Protostegidae, indicating that it may have been closer to the extinct Archelon. Unlike other sea turtles, Alienochelys' the jaws being adapted for a powerful crushing pattern well adapted for a durophagous lifestyle, as well as its unusual cranial characteristics.

<i>Apatorhamphus</i> Genus of azhdarchoid pterosaur from the Late Cretaceous

Apatorhamphus is an extinct genus of azhdarchoid pterosaur from the Kem Kem Group of Morocco. It might have been part of the Chaoyangopteridae. It is only known from a few snout fragments and it likely had a wingspan of between 3–7 metres (9.8–23.0 ft)

Zolhafah is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Western Desert of Egypt. The genus consists solely of type species Z. bella.

<i>Thalassotitan</i> Large bodied African mosasaur

Thalassotitan is an extinct genus of large mosasaurs that lived during the late Maastrichtian of the Cretaceous period in what is now Morocco, around 66 million years ago. The only known species is T. atrox, described in 2022 from fossils discovered in the Ouled Abdoun Basin, where many other mosasaurs have been found. It was assigned to the tribe Prognathodontini alongside other mosasaurs like Prognathodon and Gnathomortis. The prognathodontines are separated from other mosasaurs based on their massive jaws and robust teeth.

This list of fossil reptiles described in 2014 is a list of new taxa of fossil reptiles that were described during the year 2014, as well as other significant discoveries and events related to reptile paleontology that occurred in 2014.

References

  1. 1 2 3 4 5 6 7 8 9 Bardet, N.; Jalil, N. E.; De Lapparent De Broin, F.; Germain, D.; Lambert, O.; Amaghzaz, M. (2013). Viriot, Laurent (ed.). "A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods". PLOS ONE. 8 (7): e63586. Bibcode:2013PLoSO...863586B. doi: 10.1371/journal.pone.0063586 . PMC   3708935 . PMID   23874378.
  2. Scavezzoni, I.; Fischer, V. (2018). "Rhinochelys amaberti Moret (1935), a Protostegid Turtle from the Early Cretaceous of France". PeerJ. 10 (6): e4594. doi: 10.7717/peerj.4594 . PMC   5898427 . PMID   29666758.
  3. Evers, Serjoscha W.; Barrett, Paul M.; Benson, Roger B. J. (2019-05-01). "Anatomy of Rhinochelys pulchriceps (Protostegidae) and marine adaptation during the early evolution of chelonioids". PeerJ. 7: e6811. doi: 10.7717/peerj.6811 . ISSN   2167-8359. PMC   6500378 . PMID   31106054.