''Hymenaea mexicana'' is an extinct

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in the family

Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

described from a series of isolated

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 ...

petals Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

lets, and

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Ma ...

. The species is known from a group of

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

locations in southern

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 ...

. It is one of two extinct ''

Hymenaea ''Hymenaea'' is a genus of plants in the legume family Fabaceae. Of the fourteen living species in the genus, all but one are native to the tropics of the Americas, with one additional species (''Hymenaea verrucosa'') on the east coast of Afr ...

'' species placed close to the living species ''

Hymenaea verrucosa ''Hymenaea verrucosa'' (Zanzibar copal, East African copal, or Amber tree) is a species of flowering plant in the legume family, Fabaceae. It belongs to the paraphyletic subfamily Caesalpinioideae. It is a large tree native to the tropical regio ...

'' and along with ''

Hymenaea allendis ''Hymenaea allendis'' is an extinct legume species in the family Fabaceae described from a single isolated fossil flower in amber. The species is known from a Late Oligocene to Early Miocene location in southern Mexico. Unlike the coeval extinc ...

'', is one of the two extinct species which have been found in

Mexican amber Mexican amber, also known as Chiapas Amber is amber found in Mexico, created during the Early Miocene and middle Miocene epochs of the Cenozoic Era in southwestern North America. As with other ambers, a wide variety of taxa have been found as inc ...

History and classification

''Hymenaea mexicana'' is known from a series of fossil flowers and leaves which are inclusions in transparent chunks of Mexican amber. The species where the amber was also found in was in Brazil which could indicate where the specie Hymenaea mexicana could have been located as well. The specimens were collected over the course of twenty five years with a total of thirty amber specimens being examined for the description of the species. Mexican amber is recovered from fossil-bearing rocks in the

Simojovel Simojovel is one of the 119 municipalities of Chiapas, in southern Mexico. As of 2010, the municipality had a total population of 40,297, up from 31,615 as of 2005. It covers an area of 446.99 km2. The municipality had 145 localities, the ...

region of

Chiapas Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...

, Mexico. The amber dates from between 22.5 million years old, for the youngest sediments of the

Balumtun Sandstone The Balumtun Sandstone is a geologic formation in Chiapas, Mexico. The formation is up to 760 metres thick, and consists of gray sandstone, that were deposited during the Upper Aquitanian stage of the Early Miocene. See also * List of fossili ...

, and 26 million years old for the oldest

La Quinta Formation The La Quinta Formation is a Jurassic geologic formation which crops out in the Cordillera de Mérida and Serranía del Perijá of western Venezuela and northeastern Colombia. The formation is also present in the subsurface of the Cesar-Rancher ...

. This age range straddles the boundary between the

and

and is complicated by both formations being secondary deposits for the amber; the age range is therefore only the youngest that it might be. The fossils were examined by paleobotanists

George Poinar Jr. George O. Poinar Jr. (born April 25, 1936) is an American entomologist and writer. He is known for popularizing the idea of extracting DNA from insects fossilized in amber, an idea which received widespread attention when adapted by Michael Cr ...

Oregon State University Oregon State University (OSU) is a public land-grant, research university in Corvallis, Oregon. OSU offers more than 200 undergraduate-degree programs along with a variety of graduate and doctoral degrees. It has the 10th largest engineering co ...

and Alex Brown of

Berkeley, California Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and Emer ...

; Poinar and Brown's

description Description is the pattern of narrative development that aims to make vivid a place, object, character, or group. Description is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narr ...

of the species was published in a 2002 article in the ''

Botanical Journal of the Linnean Society The ''Botanical Journal of the Linnean Society'' is a scientific journal publishing original papers relating to the taxonomy of all plant groups and fungi, including anatomy, biosystematics, cytology, ecology, ethnobotany, electron microscopy, mo ...

''. The etymology of the chosen specific name ''mexicana'' was indicated in the type description. Insect interaction with ''Hymenaea mexicana'' was indicated in a number of the fossils examined. Several of the petals showed insect feeding damage while one of the leaves showed distinct

skeletonization Skeletonization is the state of a dead organism after undergoing decomposition.The Australian Museum. (2018). Decomposition-Body Changes. Retrieved from: https://australianmuseum.net.au/about/history/exhibitions/death-the-last-taboo/decomposit ...

, a feeding method often found in

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

ns like the family

Gracillariidae Gracillariidae is an important family of insects in the order Lepidoptera and the principal family of leaf miners that includes several economic, horticultural or recently invasive pest species such as the horse-chestnut leaf miner, ''Cameraria ...

moths. The possible pollinator for ''H. mexicana'' is suggested to be the

stingless bee Stingless bees, sometimes called stingless honey bees or simply meliponines, are a large group of bees (about 550 described species), comprising the tribe Meliponini (or subtribe Meliponina according to other authors). They belong in the family A ...

species '' Nogueirapis silacea'' based on an isolated

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

which is preserved in association with five ''N. silacea'' bees. When described, Poinar and Brown suggested Mexican amber was derived from ''H. mexicana'' resin. In 2011 another ''Hymenaea'' species, ''H. allendis'', was described from fossils also found in the amber.

Description

The leaflets of ''H. mexicana'' are an inequilateral

falcate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

shape with the

lamina Lamina may refer to: Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathematics * Laminar flow, (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption betwee ...

at the base uneven and the outside leaf margin more rounded then the inside margin. The single full leaflet is long and in width, with a leaf petiole that is long on the inside margin of the base, and

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

on the outside margin. The flowers bisexual and small, being tall and from

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

to sepal. A distinct pubescence ranging from dark brown to tan covers the flower. The preserved petals show distinct resin pockets on their surface and a distinct row of hairs along the midvein.

References

{{Taxonbar, from=Q5956414 mexicana Prehistoric angiosperms Plants described in 2002 Fossil taxa described in 2002 Oligocene plants Miocene plants Flora of Mexico Mexican amber Chattian species first appearances Miocene species extinctions Extinct flora of North America Taxa named by George Poinar Jr.