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.
The Trachypachidae are a family of beetles that generally resemble small ground beetles, but that are distinguished by the large coxae of their rearmost legs. There are only six known extant species in the family, with four species of Trachypachus found in northern Eurasia and northern North America, and two species of Systolosoma in Chile and Argentina. They were much more diverse in the past, with dozens of described species from the Mesozoic.
Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus, Arcovenator and Caletodraco have been described in France. Abelisaurids possibly first appeared during the Jurassic period based on fossil records, and some genera survived until the end of the Mesozoic era, around 66 million years ago.
Mapusaurus was a giant carcharodontosaurid carnosaurian dinosaur from Argentina during the Turonian age of the Late Cretaceous.
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. Although they have often been suggested to have acquired tribosphenic molars independently from those of Tribosphenida, this has been disputed. Fossils of australosphenidans have been found from the Jurassic of Madagascar and Argentina, and Cretaceous of Australia and Argentina. Monotremes have also been considered a part of this group in its original definition and in many subsequent studies, but its relationship with the relationship with other members has been disputed by some scholars.
Ceratodus is an extinct genus of lungfish. It has been described as a "catch all", and a "form genus" used to refer to the remains of a variety of lungfish belonging to the extinct family Ceratodontidae. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found around the world in places such as the United States, Argentina, Greenland, England, Germany, Egypt, Madagascar, China, and Australia. Ceratodus is believed to have become extinct sometime around the beginning of the Eocene Epoch.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1993.
Belonostomus is a genus of prehistoric ray-finned fish that was described by Louis Agassiz in 1844. It is a member of the order Aspidorhynchiformes, a group of fish known for their distinctive elongated rostrums.
Caypullisaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur from the Late Jurassic to the Early Cretaceous of Argentina. Its holotype was collected from the Vaca Muerta Formation of Cerro Lotena, Neuquen, dating to the early Tithonian stage of the Late Jurassic, about 150 million years ago. Caypullisaurus was first named by Marta Fernández in 1997 and the type species is Caypullisaurus bonapartei. It was a large ichthyosaur, measuring about 7 m (23 ft) long.
Dryolestida is an extinct order of mammals, known from the Jurassic and Cretaceous. They are considered basal members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they developed a fully mammalian jaw and also had the three middle ear bones. Most members of the group, as with most Mesozoic mammals, are only known from fragmentary tooth and jaw remains.
Sagenopteris is a genus of extinct seed ferns from the Triassic to late Early Cretaceous.
Notoemys is an extinct genus of platychelyid turtle known from the Late Jurassic and Early Cretaceous of the Americas.
Cymatoceras is a wide-ranging extinct genus from the nautilitacean cephalopod family, Cymatoceratidae. They lived from the Late Jurassic to Late Oligocene, roughly from 155 to 23 Ma.
Zamites is a genus of sterile foliage known from the Mesozoic of North America, Europe, India and Antarctica through the Eocene of North America. It was erected as a form taxon for leaves that superficially resembled the extant cycad Zamia, however it is now believed to belong to a similar but phylogenetically different group, the cyacadeoids (Bennettitales). The fronds are linear or lanceolate in shape, and pinnately compound, with pinnae with parallel veins and smooth margins, and symmetrical and constricted at the base where they are attached obliquely to the upper surface of the rachis. It has been interpreted as a Bennettitalean plant in the family Williamsoniaceae. It is associated with the ovulate cone Williamsonia and male cone Weltrichia.
Pterotrigonia is an extinct genus of saltwater clams, marine bivalve molluscs in the family Megatrigoniidae. This genus is known in the fossil record from the Jurassic period Tithonian age to the Cretaceous period Maastrichtian age. Species in this genus were facultatively mobile infaunal suspension feeders. The type species of the genus is Pterotrigonia cristata.
Víctor Alberto Ramos is an Argentine geologist who has contributed to the paleogeography and plate tectonics of South America. He has been a member of the Chilean Academy of Science since 2001 and won in 2013 the Premio México de Ciencia y Tecnología.
Martín Daniel Ezcurra is an Argentine palaeontologist naming many extinct genera such as Aerotitan, Lophostropheus and Powellvenator.
Artematopodidae is a family of soft-bodied plant beetles in the superfamily Elateroidea. They are mostly found in understory forest foliage. The life history of the group is obscure, larvae of the genera Eurypogon and Macropogon likely feed on moss, while the larvae of Artematopus have been fed insect remains. The oldest fossils of the family date to the Middle Jurassic.
Platychelyidae is an extinct family of pan-pleurodiran turtles, known from the Late Jurassic and Early Cretaceous of Europe, South America, North America, and the Caribbean. It represents the oldest known clade of stem-pleurodires. All known members have been found in marine or coastal deposits. Despite this, their limb morphology suggests that they were not adapted for open marine conditions, but were likely inhabitants of shallow water environments, including brackish and saline waters, and they likely never inhabited environments more marine than lagoons. Their tolerance for saline environments likely aided their dispersal during the breakup of Pangea. Unlike modern pleurodires, which retract their necks to the sides, Platychelys retracted its neck inwards, similar to modern cryptodire turtles. Platychelys is strongly morphologically similar to mata mata and snapping turtles, suggesting that it had a similar ecology as a ram or suction feeder.
Rastellum is an genus of extinct molluscs, which lived from the Middle Jurassic to the Late Cretaceous. This species is also known as Arctostrea carinata.
