The Mesozoic Era is the era of Earth's geological history, lasting from about 252 to 66 million years ago, comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of gymnosperms like, cycads, ginkgoaceae and araucarian conifers and of archosaurian reptiles, such as the dinosaurs; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic.
The Triassic is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is the first and shortest period of the Mesozoic Era and the seventh period of the Phanerozoic Eon. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic.
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. Because of their superficial resemblance to palms or ferns, they are sometimes mistaken for them, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones.
Glossopteris is the largest and best-known genus of the extinct Permian order of seed plants known as Glossopteridales. The name Glossopteris refers only to leaves, within the framework of form genera used in paleobotany.
Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.
The Hanson Formation is a geologic formation on Mount Kirkpatrick and north Victoria Land, Antarctica. It is one of the two major dinosaur-bearing rock groups found on Antarctica to date; the other is the Snow Hill Island Formation and related formations from the Late Cretaceous of the Antarctic Peninsula. The formation has yielded some Mesozoic specimens, but most of it is as yet unexcavated. Part of the Victoria Group of the Transantarctic Mountains, it lies below the Prebble Formation and above the Falla Formation. The formation includes material from volcanic activity linked to the Karoo-Ferar eruptions of the Lower Jurassic. The climate of the zone was similar to that of modern southern Chile, humid, with a temperature interval of 17–18 degrees. The Hanson Formation is correlated with the Section Peak Formation of the Eisenhower Range and Deep Freeze Range, as well as volcanic deposits on the Convoy Range and Ricker Hills of southern Victoria Land. Recent work has successfully correlated the Upper Section Peak Formation, as well unnamed deposits in Convoy Range and Ricker Hills with the Lower Hanson, all likely of Sinemurian age and connected by layers of silicic ash, while the upper section has been found to be Pliensbachian, and correlated with a greater volcanic pulse, marked by massive ash inputs.
Dicroidium is an extinct genus of fork-leaved seed plants. It is the archetypal genus of the corystosperms, an extinct group of seed plants, often called "seed ferns", assigned to the order Corystospermales or Umkomasiales. Species of Dicroidium were widely distributed and dominant over Gondwana during the Triassic. Their fossils are known from South Africa, the Arabian Peninsula, Australia, New Zealand, South America, Madagascar, the Indian subcontinent and Antarctica.
Pachypteris is a Mesozoic pteridosperm genus of fossil leaves. It has either been aligned with the peltasperms or the corystosperms.
Lepidopteris is a form genus for leaves of Peltaspermaceae, an extinct family of seed plants, which lived from around 260 to 190 million years ago, from the Late Permian to Early Jurassic. Fossils of the genus have been found across both hemispheres. Nine species are currently recognized.Lepidopteris was a common and widespread seed fern, which survived the Permian-Triassic extinction event but was largely wiped out by the Triassic-Jurassic extinction event. Lepidopteris callipteroides is especially common between the first two episodes of the Permian-Triassic extinction event, and L. ottonis forms a comparable acme zone immediately before the Triassic-Jurassic extinction event. Lepidopteris would persist into the Early Jurassic in Patagonia, represented by the species Lepidopteris scassoi.
The Peltaspermales are an extinct order of seed plants, often considered "seed ferns". They span from the Late Carboniferous to the Early Jurassic or the Jurassic-Cretaceous Boundary. It includes at least one valid family, Peltaspermaceae, which spans from the Permian to Early Jurassic, which is typified by a group of plants with Lepidopteris leaves, Antevsia pollen-organs, and Peltaspermum ovulate organs, though the family now also includes other genera like Peltaspermopsis, Meyenopteris and Scytophyllum. Along with these, two informal groups of uncertain taxonomic affinities exist, each centered around a specific genus ; Supaia and Comia, known from the Early Permian of the Northern Hemisphere, especially of North America. Both the "Comioids" and the "Supaioids" are associated with the peltaspermacean ovulate organ Autunia. The Late Triassic-Middle Jurassic genus Pachydermophyllum may also have affinities to the peltasperms.
Umkomasia is a genus of seed bearing organs produced by corystosperm seed ferns, first based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. He recognized on the basis of cuticular similarities that the same plant produced pollen organs Pteruchus and the leaves Dicroidium. Various other corystosperm seed bearing organs from the Jurassic and Cretaceous have been assigned to this genus, but recently have been given distinct genera, with Umkomasia being restricted to the Triassic.
Umkomasia macleanii is an ovulate structure of a seed fern (Pteridospermatophyta and the nominate genus of Family Umkomasiaceae. It was first described by Hamshaw Thomas from the Umkomaas locality of South Africa.
Pteruchus africanus is a pollen organ of a seed fern (Pteridospermatophyta). It was first described by Hamshaw Thomas from the Umkomaas locality of South Africa.
Umkomasia feistmantelii is an unusually large species of Umkomasia from the Early Triassic of New South Wales, Australia.
Pteruchus is a form genus for pollen organs of the seed fern (Pteridospermatophyta family Umkomasiaceae. It was first described by Hamshaw Thomas from the Umkomaas locality of South Africa. It is associated with the seed bearing organs Umkomasia and Dicroidium leaves.
This article records new taxa of plants that are scheduled to be described during the year 2018, as well as other significant discoveries and events related to paleobotany that occurred in the year 2018.
The Mawson Formation is a geological formation in Antarctica, dating to roughly between 182 and 177 million years ago and covering the Toarcian stages of the Jurassic Period in the Mesozoic Era. Vertebrate remains are known from the formation. The Mawson Formation is the South Victoria Land equivalent of the Karoo Large Igneous Province in South Africa, as well the Lonco Trapial Formation and the Cañadón Asfalto Formation of Argentina. The Volcanic material was likely sourced from the Antarctic Peninsula´s Ellsworth Land Volcanic Group.
Ctenis is a genus of fossil foliage attributable to the Cycadales, being one of the most common genera of cycad fossil leaves in the Mesozoic.
The Umm Irna Formation is a geological formation in Jordan. It is found in several outcrops in Jordan in the area around the eastern shore of the Dead Sea. It is Late Permian in age, and is the oldest unit in the succession, overlying the Cambrian aged Umm Ishrin Sandstone Formation. The formation predominantly consists of sandstones, claystones and mudstones deposited in fluvial and lacustrine conditions. The formation is of considerable paleobotanical interest, as it preserves the earliest known remains of plant groups that would become widespread during the Mesozoic, including corystosperm "seed ferns", represented by the widespread Triassic genus Dicroidium, cycads, conifers, as well as Bennettitales. Other plant groups present in the formation include Noeggerathiales, gigantopterids, lyginopterids and possible ginkgophytes.
Komlopteris is an extinct genus of "seed fern" with possible corystosperm affinities. Fossils have been found across both hemispheres, dating from the latest Triassic to the early Eocene (Ypresian), making it the youngest "seed fern" in the fossil record.
