# Genetics/Paleobotany

Paleobotany is the study of plant or plant-like fossils.
The Lepidodendrales, quillwort-like large tree-like plants from the Carboniferous also left fossils in bituminous coal as on the left.
Def. the "branch of paleontology that deals with the study of plant fossils" is called paleobotany.
"The groups could then be arranged from the dominant group (first rank) to the least common group (fifth rank)."
"The dominant group in the Palaeozoic microplankton is the Acritarcha."
"Pteridophyta is the second dominant group."
"The angiosperms are both the dominant group of land plants and by far the most important plants for human use."
"Statistical analyses indicate that the Phanerozoic history of vascular land plants (tracheophytes) may be interpreted in terms of the successive radiations of four major plant groups, each characterized by a common morphological and/or reproductive grade. Following initial invasion of the land, the diversification of each group coincides with a decline in species numbers of the previously dominant group."

## Asteroxylaceae

Asteroxylon ("star-shaped xylem") is an extinct genus of vascular plants of the Division Lycopodiophyta known from anatomically preserved specimens described from the famous Early Devonian Rhynie chert and Windyfield chert in Aberdeenshire, Scotland. Asteroxylon is considered the most basal member of the Lycopsida.
This plant consisted of aerial, isotomously and anisotomously branching stems that reached 12 mm in diameter and 40 cm in length. The possibly procumbent aerial stems arose from a leaf-less rhizome which bore smaller-diameter, positively geotropic root-like branches. The rhizomes, which represent an independent origin of roots, reached a depth of up to 20 cm below the surface. The xylem or conducting tissue at the center of the aerial stems is distinctly star-shaped in cross-section and has been considered an early actinostele or an "Asteroxylon-type" protostele. The tracheids are of the primitive annular or helical type (so-called G-type). "Leaves" – not true leaves, but protrusions – were of the form of unbranched strap-shaped enations up to 5 mm long; a single vascular trace branched from the main bundle in the centre of the stem to terminate at the base of each enation. Enations and axes bore stomata, indicating that their tissues were capable of photosynthesis.
Asteroxylon differs from other similar Early Devonian lycopsids such as Drepanophycus and Baragwanathia in that the singular vascular leaf trace in these latter plants extends into the leaf. The leaves of Drepanophycus and Baragwanathia are therefore considered to be true microphylls or, alternatively, small leaves.
The type species is Asteroxylon mackiei.

## Betulaceae

Betula leopoldae fossils have been identified from a number of locations in Western North America, the 49 mya Klondike Mountain Formation near Republic, Washington along with the Allenby Formation near Princeton, British Columbia, the Falkland fossil site near Falkland, British Columbia, and McAbee Fossil Beds both of the Kamloops Groups Tranquille Formation, and the Quilchena fossil site near Quilchena, British Columbia.
In general, the geologic ages for the Okanagan Highland locations are of Early Eocene, with the sites that have current uranium-lead dating or argon–argon dating radiometric dates indicating Ypresian ages, while the undated sites or those given older dates being possibly slightly younger and Lutetian in age.
Betula leopoldae was described from a series of type specimens collected in the Republic, Washington area during the early 1980s. The paratype leaf, UW 31256 plus the holotype leaf UW 39722, are in the paleobotanical collections of Burke Museum, while the counterpart for the holotype, UCMP 9286 is in the University of California Museum of Paleontology in California. Working from these two specimens, the species was studied by Jack A. Wolfe of the University of California and Wesley C. Wehr of the Burke Museum. They published their 1987 type description in a United States Geological Survey monograph on the North Eastern Washington dicot fossils. The specific epithet leopoldae is a matronym recognizing paleobotanist and conservationist Estella Leopold, though this was not noted in the type description. In a paper which appeared that same year, Peter Crane and Ruth Stockey described a series of B. leopoldae leaves along with catkins, flowering bodies, and pollen from the Allenby Formation. Crane and Stockey noted B. leopoldae to be the oldest reproductive plus vegetative record for a Betula species at that time. A B. leopoldae leaf from the Klondike mountain formation was figured by Conrad Labandeira in 2002 which displayed distinct interior foliage feeding damage from insect feeding, in which a series of four leaf blade sections had been removed between successive secondary veins.

## Calamitaceae

"Specimens of Calamites cistii (Sphenophyta; Pennsylvanian, France) are described showing endophytic cavities, located in the outer cortex of the stem, a tissue that is rarely preserved. This new record shifts the appearance of this behavior back 60 Ma." Two "specimens of the arborescent Calamites cistii (Sphenophyta) [were] collected from the Pennsylvanian basin of Graissessac (Hérault, France)". "The specimens belong to the species Calamites cistii Brongniart, 1828 (Sphenophyta). They are housed in the Collections de Paléobotanique, Service général des Collections, University Montpellier 2 (LPM)."

## Ginkgoaceae

The image at the right shows fronds impressed onto shale in a specimen on display at the Paläontologische Museum München. The fossil is from Scalby Ness, Scarborough, England.
Ginkgo huttonii is an extinct Ginkgo species from the Jurassic of England, also known by the name, Ginkgoites huttonii, the genus, Ginkgoites, referring to a group of extinct members of the Ginkgoaceae, where G. huttonii was a broad-leaved, deciduous gymnosperm bearing resemblance to the only living member of the Ginkgoaceae, Ginkgo biloba.
Ginkgo huttonii is known largely by compression fossils of its leaves similar to other members of the Ginkgoites, the fossil leaves are simple, four-lobed, and have dense, radially disposed venation. G. huttonii fossil seeds are frequently found as well as at least a few fossilized male catkins. G. huttonii wood has yet to be described but it is likely the plant was similar to the extant, G. biloba, with wood akin to that of modern day conifers.
G. huttonii is heavily represented in the Jurassic flora of Yorkshire, England - a flora which has been studied in depth since the 1800s. The order Ginkgoales had a wide distribution throughout the northern hemisphere from the Lower Jurassic through the Cretaceous.

## Neurodontopteridaceae

Neuropteris, a fern, leaf impressions and fossils occur in bituminous coal such as in the image on the right. These coal seams and strata are dated to the Carboniferous period.
Neuropteris is an extinct Pteridospermatophyta (seed fern) that existed in the Carboniferous period, known only from fossils.
Major species include Neuropteris loschi.

## Theaceae

The earliest fossil record of Camellia are the leaves of †C. abensis from the upper Eocene of Japan, †C. abchasica from the lower Oligocene of Bulgaria and †C. multiforma from the lower Oligocene of Washington, United States.

## Hypotheses

* Plant classification before genomics may not agree with classification after application of genomics.