Alkaidia

Last updated

Alkaidia
Temporal range: Barremian–Cenomanian
Asteroidea (10.5852-ejt.2021.755.1405) Figure 16 A-B.png
Fossil of A. sumralli
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Forcipulatida
Family: Terminasteridae
Genus: Alkaidia
Blake & Reid, 1998
Type species
Alkaidia sumralli
Blake & Reid, 1998
Other species
  • A. megaungulaEwin & Gale, 2020

Alkaidia is an extinct genus of sea stars which lived in the western Tethys Ocean from the Barremian to Cenomanian stages of the Cretaceous period. It was first described in 1998, and two species are currently assigned to it. The type species, A. sumralli, is known from both complete and fragmentary specimens collected in Texas, and fossils of an earlier species, A. megaungula, have been found in Morocco.

Discovery and naming

The fossilized remains of Alkaidia were first described by paleontologists Daniel B. Blake and Robert Reid, III in a 1998 publication describing some Albian-aged starfish fossils from north-central Texas. The authors determined that over 50 specimens (some complete and other fragmentary) originating from the Washita Group represented a new genus and species which they named Alkaidia sumralli. The generic name references Alkaid, a star in the constellation Ursa Major, while the specific name honors Colin Sumrall, who discovered and prepared some of the specimens, including the holotype. A complete specimen (1786TXI) found in deposits of the Del Rio Formation at Waco Dam Quarry was designated as the holotype, and was placed in the Texas Memorial Museum. Some additional fragments from the same locality and from the Paw Paw Formation were designated as paratypes. [1]

A second species of Alkaidia was described in 2020 by paleontologists Timothy A. M. Ewin and Andrew S. Gale based on material originating from the Taba Starfish Bed of the Barremian-aged Taboulouart Formation in Morocco and purchased from commercial fossil collectors. This species was named Alkaidia megaungula, the specific name meaning "large hoof" in Greek and referencing the large terminal ossicle of this species, which resembles a hoof. The studied specimens are well-preserved and represent numerous individuals of various growth stages, allowing an ontogenetic series to be shown. [2]

Related Research Articles

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

Sarcosuchus is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the early Albian, 133 to 112 million years ago of what is now Africa and South America. The genus name comes from the Greek σάρξ (sarx) meaning flesh and σοῦχος (souchus) meaning crocodile. It was one of the largest pseudosuchians, with the largest specimen of S. imperator reaching approximately 9–9.5 metres (29.5–31.2 ft) long and weighing up to 3.45–4.3 metric tons. It is known from two species; S. imperator from the early Albian Elrhaz Formation of Niger, and S. hartti from the Late Hauterivian of northeastern Brazil. Other material is known from Morocco and Tunisia and possibly Libya and Mali.

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

Leaellynasaura is a genus of small herbivorous ornithischian dinosaurs from the late Aptian to early Albian stage of the Early Cretaceous, around 118-110 million years ago. It was first discovered in Dinosaur Cove, Australia. The only known species is Leaellynasaura amicagraphica. It was described in 1989, and named after Leaellyn Rich, the daughter of the Australian palaeontologist couple Tom Rich and Patricia Vickers-Rich who discovered it. The specific name, amicagraphica, translates to "friend writing" and honours both the Friends of the Museum of Victoria and the National Geographic Society for their support of Australian paleontology.

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

Limaysaurus is a genus represented by a single species of rebbachisaurid sauropod dinosaurs, which lived during the mid-Cretaceous period, about 99.6 to 97 million years ago, in the Cenomanian, in what is now South America.

Calamospondylus is a genus of theropod dinosaur. It lived during the Early Cretaceous and its fossils were found on the Isle of Wight in southern England. The type species is C. oweni.

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

Texasetes is a genus of ankylosaurian dinosaurs from the late Lower Cretaceous of North America. This poorly known genus has been recovered from the Paw Paw Formation near Haslet, Tarrant County, Texas, which has also produced the nodosaurid ankylosaur Pawpawsaurus.

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

Erectopus is an extinct genus of basal allosauroid theropod from the Early Cretaceous La Penthiève Beds Formation of France and also possibly the Cernavodă Formation of southern Romania. The type species is E. superbus, which was initially known as a species of Megalosaurus.

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

Brachauchenius is an extinct genus of pliosaurid that lived in North America and Morocco during the Late Cretaceous.

<i>Axelrodichthys</i> Extinct genus of coelacanths

Axelrodichthys is an extinct genus of mawsoniid coelacanth from the Cretaceous of Africa, North and South America, and Europe. Several species are known, the remains of which were discovered in the Lower Cretaceous (Aptian-Albian) of Brazil, North Africa, and possibly Mexico, as well as in the Upper Cretaceous of Morocco (Cenomanian), Madagascar and France. The Axelrodichthys of the Lower Cretaceous frequented both brackish and coastal marine waters while the most recent species lived exclusively in fresh waters. The French specimens are the last known fresh water coelacanths. Most of the species of this genus reached 1 metre to 2 metres in length. Axelrodichthys was named in 1986 by John G. Maisey in honor of the American ichthyologist Herbert R. Axelrod.

The Paw Paw Formation is a geological formation in Texas whose strata date back to the late Albian stage of the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.

<i>Uktenadactylus</i> Genus of anhanguerid pterosaur from the Early Cretaceous

Uktenadactylus is a genus of anhanguerid pterodactyloid pterosaurs from the Lower Cretaceous Paw Paw Formation of Texas, United States and the Wessex Formation on the Isle of Wight, England. Fossil remains of Uktenadactylus dated back to the Early Cretaceous period, from about 125 to 100 million years ago.

<i>Betelgeusia</i> Extinct genus of starfishes

Betelgeusia is an extinct genus of sea stars in the family Radiasteridae. It was described by Blake and Reid, in 1998, and existed in what is now the Netherlands, Texas, United States, Morocco, and India, during the Middle Jurassic through the Cretaceous period. It contains the species B. brezinai, B. exposita, B. riedi, and B. orientalis.

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

Leyvachelys is an extinct genus of turtles in the family Sandownidae from the Early Cretaceous of the present-day Altiplano Cundiboyacense, Eastern Ranges, Colombian Andes. The genus is known only from its type species, Leyvachelys cipadi, described in 2015 by Colombian paleontologist Edwin Cadena. Fossils of Leyvachelys have been found in the fossiliferous Paja Formation, close to Villa de Leyva, Boyacá, after which the genus is named. The holotype specimen is the oldest and most complete sandownid turtle found to date.

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

Galleonosaurus is a genus of basal ornithopod dinosaur from the Wonthaggi Formation of the Gippsland region of Victoria, Australia. The type and only species is Galleonosaurus dorisae.

<i>Targaryendraco</i> Genus of targaryendraconian pterosaur from the Early Cretaceous

Targaryendraco is a genus of pterodactyloid pterosaur from the Early Cretaceous period of Hannover, northern Germany. Fossil remains of Targaryendraco dated back about 132 million years ago.

<i>Afrotapejara</i> Genus of tapejarid pterosaur from the Late Cretaceous period

Afrotapejara is an extinct genus of tapejarid pterosaur discovered in Morocco. The type species, Afrotapejara zouhri, was named and described in 2020. It was the first tapejarid discovered in Africa and the fourth pterosaur discovered in the Kem Kem Beds.

<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)

<i>Leptostomia</i> Genus of azhdarchoid pterosaur from the Cretaceous period

Leptostomia is a genus of long-beaked pterosaur from the mid-Cretaceous (Cenomanian) of Morocco, North Africa. The type species is L. begaaensis, which was named and described in 2021 from sediments of the Kem Kem Group in Morocco. It was a small animal with a long, slender bill which is thought to have been used to probe sediments for worms and other invertebrates, similar to kiwi birds and curlews. Leptostomia is likely a member of the Azhdarchoidea.

<i>Villebrunaster</i> Extinct genus of echinoderms

Villebrunaster is an extinct genus of starfish-like animal belonging to Asterozoa that lived around 480 million years ago during Early Ordovician Period in modern-day southern France and Morocco. As of 2022, it contains two species, namely V. thorali and V. fezouataensis. V. thorali was described in 1951 and V. fezouataensis was described in 2021. Villebrunaster represents one of the oldest members of asterozoans, and perhaps, according to a description in 2021, the earliest divergent stem-group of Asterozoa.

<span class="mw-page-title-main">Terminasteridae</span> Extinct family of starfish

Terminasteridae is a family of fossil starfish which lived from the Jurassic to Cretaceous periods. It was erected in 2011 as a monotypic group to contain only the type genus Terminaster. A second genus, Alkaidia, was originally described as a member of the extant family Benthopectinidae, but was transferred to Terminasteridae in 2020.

References

  1. Blake, Daniel B.; Reid, Robert (1998). "Some Albian (Cretaceous) asteroids (Echinodermata) from Texas and their paleobiological implications". Journal of Paleontology . 72 (3): 512–532. Bibcode:1998JPal...72..512B. doi:10.1017/S002233600002429X. JSTOR   1306650. S2CID   131483454.
  2. Ewin, Timothy A. M.; Gale, Andrew S. (September 2020). "Asteroids (Echinodermata) from the Barremian (Lower Cretaceous) of the Agadir Basin, west Morocco". Journal of Paleontology. 94 (5): 931–954. doi:10.1017/jpa.2020.20. ISSN   0022-3360.