''Eucommia constans'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the family

Eucommiaceae ''Eucommia'' is a genus of small trees now native to China, with a fossil record that shows a much wider distribution. The single living species, ''Eucommia ulmoides'', is near threatened in the wild, but is widely cultivated in China for its ...

. ''

Eucommia ''Eucommia'' is a genus of small trees now native to China, with a fossil record that shows a much wider distribution. The single living species, ''Eucommia ulmoides'', is near threatened in the wild, but is widely cultivated in China for its ...

'' is a genus of small

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s now

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, with a fossil record that shows a much wider distribution. ''E. constans'' is known from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

fruits found in

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

deposits of east-central Mexico. ''E. constans'' is one of five described fossil species from North America assigned to the modern genus ''Eucommia''. The other species are '' E. eocenica'', '' E. jeffersonensis'', '' E. montana'', and '' E. rowlandii''.

History and classification

''Eucommia constans'' was first identified by Susana Magallón-Puebla and Sergio R. S. Cevallos-Ferriz in 1994 from the Miocene to Pleistocene Pié de Vaca Formation which outcrops in the state of

Puebla Puebla ( en, colony, settlement), officially Free and Sovereign State of Puebla ( es, Estado Libre y Soberano de Puebla), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 217 municipalities and its cap ...

in East-central

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The species is the only record of the genus ''Eucommia'' in Mexico, and is the youngest occurrence of ''Eucommia'' in North America. ''E. constans'' is also the southernmost occurrence of ''Eucommia'' in North America, and when first described the species was the southernmost species to be described in world. The species was described from a group of over one-hundred and fifty

compression fossil A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason fo ...

s studied by Magallón-Puebla and Cevallos-Ferriz who published their findings in an ''

International Journal of Plant Sciences The ''International Journal of Plant Sciences'' covers botanical research including genetics and genomics, developmental and cell biology, biochemistry and physiology, morphology and structure, systematics, plant-microbe interactions, paleobotany, ...

'' article. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen, IGM-PB 2573–632, is preserved in the paleontological collections housed in the Instituto Geologica which is part of the

National Autonomous University of Mexico The National Autonomous University of Mexico ( es, Universidad Nacional Autónoma de México, UNAM) is a public research university in Mexico. It is consistently ranked as one of the best universities in Latin America, where it's also the bigges ...

Mexico City Mexico City ( es, link=no, Ciudad de México, ; abbr.: CDMX; Nahuatl: ''Altepetl Mexico'') is the capital and largest city of Mexico, and the most populous city in North America. One of the world's alpha cities, it is located in the Valley o ...

, Mexico.

Description

The ellipsoidal fruits of ''E. constans'' range from in length and they vary in width from with a typically tapering and long stipe. While the tip of the fruit is quite rounded, the stigmatic notch is placed off center from the tip. While very similar in appearance to ''E. montana'' the two are distinguishable by the larger size and longer stipe of ''E. constans''. ''E. eocenica'' is larger than ''E. constans'' and is notably different in the structure of the fruit tip, which is distinctly pointed rather than rounded as seen in ''E. constans''.

References

External links

{{Taxonbar, from=Q5406186 †Eucommia constans Flora of Mexico Prehistoric angiosperms Miocene plants Pliocene plants Pleistocene plants Neogene Mexico Quaternary Mexico Miocene North America Pliocene North America Pleistocene North America Flora of Puebla Fossil taxa described in 1994 Plants described in 1994 Extinct flora of North America