Superlucina megameris

Superlucina megameris
Superlucina megameris (from Dall 1901b: Plate 42, Fig. 1)
Temporal occurrence
Upper Eocene
38 to 33.9 million years
Locations
Jamaica, Curacao, Saint Barthélemy, Panama, Florida
Systematics
Superordinate : Imparidentia Order : Lucinida Superfamily : Lucinoidea Family : Moon mussels (Lucinidae) Genre : Superlucina Type : Superlucina megameris
Scientific name of the  genus
Superlucina
Taylor & Glover , 2009
Scientific name of the  species
Superlucina megameris
( Dall , 1901)

Superlucina megameris is an extinct shellfish -Art from the family of lucinidae (Lucinidae). It wasfoundin strata of the Eocene in Jamaica . It is the type and only species of the genus Superlucina Taylor & Glover, 2009. With a height of 31 cm, Superlucina megameris is also the largest species of moon mussels found to date.

features

The housing , which has the same shape and is egg-shaped , reaches a height of over 31 cm and a length of 28 cm (the specimen was, however, incomplete in length). The height is greater than the length in a ratio of 1.06 to 1.1. The case measures 8.6 cm in cross-section and thickness. The narrow, posterior dorsal margin drops off steeply and is delimited by a radial keel that pulls towards the posterior end of the ventral margin. The anterior dorsal margin is almost straight, sloping flatter, and is only slightly set off by a weak keel. The vertebrae are narrow but strong. There is no pronounced lunula , but there is a lanceolate pit in front of the vertebrae. In contrast, the area is wide and deep, and delimited by raised slats. The great ligament is external and behind the vertebrae. The lock is without teeth. The anterior sphincter is extraordinarily long, narrow, and curved. It runs parallel to the mantle edge, but is more than 90% of the course it is separated from the mantle edge. The rear end is behind the centerline of the case. The front end is slightly widened. The posterior sphincter is large and irregularly triangular in cross section. The surface line is complete with numerous, lobed projections. The inner stripe along the mantle line shows circular scars resulting from the attachment of the mantle.

The shell of the largest specimen is about 3 mm thick at the edge of the case, and even 13 mm thick near the rear sphincter. In the middle of the housing, the shell thickness is 5 mm. The ornamentation consists of low, roughened lamellas parallel to the edge with growth stripes. There are no radial elements on the outside. but in juvenile specimens there are fine radial stripes. The outside edge of the casing is essentially smooth, with a few fine radial pits. In the rear part of the housing, a sloping bead and a pit ventrally below the rear sphincter mark the position of the rear opening in the jacket.

Geographical distribution, geological age and habitat

The holotype is from Jamaica. The species has also been found in other localities in the Gulf of Mexico and the Caribbean : the Upper Ocene Ceru di Cueba Formation of Curaçao , the Lezard Limestone Member (Middle Eocene) of Saint-Barthélemy , Lesser Antilles, the Upper Ocene of the Dominican Republic and the Upper Ocene Gatuncillo Formation of Panama and the Upper Ocene Moodys Branch Formation of Florida (USA).

At a locality in Jamaica ( Claremont ) numerous specimens of Superlucina megameris were found in their living position. The two flaps were still connected and stuck vertically with the rear end down in the sedimentary rock.

Taxonomy

The taxon was first described in 1901 by William Healey Dall as Lucina megameris . It is the type and only species of the genus Superlucina Taylor & Glover, 2009.

supporting documents

Literature

• John D. Taylor, Emily A. Glover: A giant lucinid bivalve from the Eocene of Jamaica - Systematics, life habits and chemosymbiosis (Mollusca: Bivalvia: Lucinidae). Palaeontology, 52 (1): 95-109, 2009 doi : 10.1111 / j.1475-4983.2008.00839.x

Individual evidence

1. ^ William Healey Dall: Synopsis of the Lucinacea and of the American species. Proceedings of the US National Museum, 23: 779-833, 1901
2. ^ William Healey Dall: A gigantic fossil Lucina. The Nautilus, 15: 40-42, 1901 Online at www.biodiversitylibrary.org