Montrichardia aquatica
Encyclopedia
Montrichardia aquatica is an extinct species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of monocot
Monocotyledon
Monocotyledons, also known as monocots, are one of two major groups of flowering plants that are traditionally recognized, the other being dicotyledons, or dicots. Monocot seedlings typically have one cotyledon , in contrast to the two cotyledons typical of dicots...

 plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in the Araceae
Araceae
Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe or leaf-like bract. Also known as the Arum family, members are often colloquially...

 family . M. aquatica is related to the living species M. arborescens
Montrichardia
Montrichardia is a genus of flowering plants in the Araceae family. It contains two species, Montrichardia arborescens and Montrichardia linifera, and one extinct species Montrichardia aquatica...

and M. linifera
Montrichardia
Montrichardia is a genus of flowering plants in the Araceae family. It contains two species, Montrichardia arborescens and Montrichardia linifera, and one extinct species Montrichardia aquatica...

. The species is solely known from the Middle to late Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 (about 60 to 58 Ma), Cerrejón Formation
Cerrejón Formation
The Cerrejón Formation is a geologic formation in Colombia dating back to the Middle-Late Paleocene. It is found in the El Cerrejón subbasin of the Racheria basin of La Guajira. The formation consists of bituminous coal fields that are an important economic resource. Coal from the Cerrejón...

 deposits in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

.

History and classification

The species is known only from the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 specimen, number ING-0904, and the four paratypes ING-0808, ING-0903, ING-0905 and ING-0906. The leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...

 are currently residing in the collections housed by the Colombian Geological Institute in Bogotá, Colombia. All five fossil specimens were collected from Cerrejón Formation
Cerrejón Formation
The Cerrejón Formation is a geologic formation in Colombia dating back to the Middle-Late Paleocene. It is found in the El Cerrejón subbasin of the Racheria basin of La Guajira. The formation consists of bituminous coal fields that are an important economic resource. Coal from the Cerrejón...

 exposures in the Cerrejón coal mine, located in the Rancheria Basin, Colombia. They were first studied by a group of researchers from Florida Museum of Natural History
Florida Museum of Natural History
The Florida Museum of Natural History is the State of Florida's official state-sponsored and chartered natural history museum. Its main facilities are located on the campus of the University of Florida in Gainesville, Florida....

, the Smithsonian Museum of Natural History and led by Fabiany Herrera from the Smithsonian Tropical Research Institute
Smithsonian Tropical Research Institute
The Smithsonian Tropical Research Institute in Panama, the only bureau of the Smithsonian Institution based outside of the United States, is dedicated to understanding biological diversity. What began in 1923 as small field station on Barro Colorado Island in the Panama Canal Zone has developed...

. Herrera and associates published their 2008 type description in the American Journal of Botany
American Journal of Botany
The American Journal of Botany is a peer-reviewed scientific journal which includes research papers on all aspects of plant biology. It is published by the Botanical Society of America on a monthly basis since 1914....

. The specific epithet "aquatica" a derivation of the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 "aquaticus" was chosen by the authors in reference to the species having lived near to, or in water.

Description

There are two angiosperm families, Nymphaeaceae
Nymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...

 and Nelumbonaceae which have leaf shapes very similar to Montrichardia aquatica. Though the over all shape of leaves in those families may be similar the vein structure in M. aquatica is notably distinct from both. Neither family possesses the collective veins along the margin, naked secondary veins along the basal margin, and the distinct higher vein structure that is present in the fossil specimens of M. aquatica. This combination of features is found within the family Araceae. M. aquatica is placed within the living Araceae genus Montrichardia
Montrichardia
Montrichardia is a genus of flowering plants in the Araceae family. It contains two species, Montrichardia arborescens and Montrichardia linifera, and one extinct species Montrichardia aquatica...

due to the unique combination of leaf morphology characters present in the fossils. Though the fossils are generally similar to the fossil genus Caladiosoma the vein structure is very dissimilar and thus is not considered a close relation. Overall the species possesses entire margined leaves with a generally ovate shape. The leaf apex is short and rounded, while the base is heart to arrowhead shaped. Each of the basal lobes is supplied by a secondary vein which forms part of the margin and forks several times. The overall size of the leaves reached up to 56 by.

Several depositional environments appeared to have hosted M. aquatica. The holotype specimen was recovered from a sandstone that probably was an overbank deposits of a fluvial environment. The paratype specimens were recovered from gray siltstones underlying one of the thickest coal sequences in the Cerrejón Formation. These layers are most likely from a swampy to lake like environment.
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