''Orontium mackii'' is an extinct golden club

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

Araceae The 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). A ...

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 ...

leaves. The species is known from

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

sediments exposed in the state of

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...

in the

United States of America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...

. It is one of several extinct species placed in the living golden-club genus ''

Orontium ''Orontium'' , sometimes called golden-club, is a genus of flowering plants in the family Araceae. The single living species in the genus is '' Orontium aquaticum'', while the two other described species, '' Orontium mackii'' and '' Orontium wolf ...

''.

History and classification

''Orontium mackii'' has been identified from a series of three exposures in the Jose Creek member of the

McRae Formation The McRae Formation is a geological formation exposed in southern New Mexico whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. Description The formation consists o ...

. These outcrops, near

Truth or Consequences, New Mexico Truth or Consequences (often abbreviated as T or C) is a city in New Mexico, and the county seat of Sierra County. In 2020, the population was 6,052. It has frequently been noted on lists of unusual place names for having chosen to rename itse ...

, are all from the same horizon of a volcanic ash fall and are separated by a distance of , preserving a warm to subtropical environment in and along a river system. The Jose Creek member is dated as probable

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

, based on the conformable contact between the Jose Creek member and the overlying Hall Creek member. In addition the site hosts a grouping of conifer megafossils which is comparable to that found in other southern and central North American fossil sites of Maastrichtian age. Of the three sites from which ''O. mackii'' is known, two preserve a typical wet environment which had standing water and wet soil conditions, as is seen in modern '' O. aquaticum'' habitats. The third site for ''O. mackii'' differs, being found in a paleo-flood plain, which was made up of well-drained soils and no obligate aquatic plants. If this is a correct interpretation, it has been suggested that, unlike the other two species in the genus, ''O. mackii'' was not dependent on wetland or aquatic conditions for survival. Orontium aquaticum 1 - Buffalo Botanical Gardens

Orontium aquaticum 1 - Buffalo Botanical Gardens

The species was described from a

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

, 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 sever ...

TXSTATE-1001, and a group of five

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...

s, all of which are currently preserved in the paleobotanical collections housed at the

Texas State University Texas State University is a public research university in San Marcos, Texas. Since its establishment in 1899, the university has grown to the second largest university in the Greater Austin metropolitan area and the fifth largest university ...

, in San Marcos, Texas. The specimens were studied by a group of

paleobotanist Paleobotany, which is also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeogr ...

s led by Josef Bogner, with the team publishing their 2007 type description for ''O. mackii'' in the Journal ''Zitteliana''. The

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

of the chosen specific name ''mackii'' is in recognition of Gregory H. Mack, in honor of his longtime contributions to New Mexico geology, and for discovering the site which produced ''O. mackii''.

Description

The leaves of ''O. mackii'' are an elliptical oblong shape overall, being over long, though the full length is unknown. The leaves range from in width, with a leaf petiole that is over long. The leaf tips are not known, due to the incomplete nature of the fossils found. As such, it is not certain whether ''O. mackii'' had leaf tips which were hooded in shape as are the leaves of both ''O. wolfei'' and ''O. aquaticum''. The lateral veins of the leaves are composed of only two orders and are connected by a single order of crossveins while the midrib of the leaves is most distinct towards the leaf base. In the fossils the midrib is noted for a tendency to accumulate iron oxides.

References

{{Taxonbar, from=Q7103803 Orontioideae Plants described in 2007 Fossil taxa described in 2007 Late Cretaceous plants Flora of New Mexico Extinct flora of North America Cretaceous angiosperms