Mesozoic

Plateosaurus (a prosauropod)
Sericipterus
Stegosaurus
Tylosaurus (a mosasaur) hunting Xiphactinus
Conifers were the dominant terrestrial plants for most of the Mesozoic, with grass becoming widespread in the Late Cretaceous. Flowering plants appeared late in the era but did not become widespread until the Cenozoic.
Dinosaurs were the dominant terrestrial vertebrates throughout much of the Mesozoic.

Second-to-last era of Earth's geological history, lasting from about and comprising the Triassic, Jurassic and Cretaceous Periods.

- Mesozoic
Plateosaurus (a prosauropod)

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Permian–Triassic boundary at Frazer Beach in New South Wales, with the End Permian extinction event located just above the coal layer

Permian–Triassic extinction event

Permian–Triassic boundary at Frazer Beach in New South Wales, with the End Permian extinction event located just above the coal layer
Shell bed with the bivalve Claraia clarai, a common early Triassic disaster taxon.
Sessile filter feeders like this Carboniferous crinoid, the mushroom crinoid (Agaricocrinus americanus), were significantly less abundant after the P–Tr extinction.
Lystrosaurus was by far the most abundant early Triassic land vertebrate.
Map of Pangaea showing where today's continents were at the Permian–Triassic boundary

The Permian–Triassic (P–T, P–Tr) extinction event, also known as the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras, approximately 251.9 million years ago.

Basilosaurus

Cenozoic

Earth's current geological era, representing the last 66million years of Earth's history.

Earth's current geological era, representing the last 66million years of Earth's history.

Basilosaurus
Megafauna of Pleistocene Europe (mammoths, cave lions, woolly rhino, reindeer, horses)

It is the latest of three geological eras since complex life evolved, preceded by the Mesozoic and Paleozoic.

Trilobites

Paleozoic

Earliest of three geologic eras of the Phanerozoic Eon.

Earliest of three geologic eras of the Phanerozoic Eon.

Trilobites
Cephalaspis (a jawless fish)
Eogyrinus (an amphibian) of the Carboniferous
Synapsid: Dimetrodon
Life in the early Paleozoic
Swamp forest in the Carboniferous
An artist's impression of early land plants

The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.

Discoscaphites iris ammonite from the Owl Creek Formation (Upper Cretaceous), Owl Creek, Ripley, Mississippi

Cretaceous–Paleogene extinction event

Sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago.

Sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago.

Discoscaphites iris ammonite from the Owl Creek Formation (Upper Cretaceous), Owl Creek, Ripley, Mississippi
Rudist bivalves from the Late Cretaceous of the Omani Mountains, United Arab Emirates. Scale bar is 10 mm.
Kronosaurus Hunt, a rendering by Dmitry Bogdanov in 2008. Large marine reptiles, including plesiosaurians such as these, became extinct at the end of the Cretaceous.
Tyrannosaurus was among the dinosaurs living on Earth before the extinction.
Hell Creek Formation
The K–Pg boundary exposure in Trinidad Lake State Park, in the Raton Basin of Colorado, shows an abrupt change from dark- to light-colored rock.
Radar topography reveals the 180 km-wide ring of the Chicxulub crater.
Artistic impression of the asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatán Peninsula in what is today Southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 66 million years ago, is believed to have caused the mass extinction of dinosaurs and many other species on Earth. The impact spewed hundreds of billions of tons of sulfur into the atmosphere, producing a worldwide blackout and freezing temperatures which persisted for at least a decade.
The river bed at the Moody Creek Mine, 7 Mile Creek / Waimatuku, Dunollie, New Zealand contains evidence of a devastating event on terrestrial plant communities at the Cretaceous–Paleogene boundary, confirming the severity and global nature of the event.
An artist's rendering of Thescelosaurus shortly after the K–Pg mass extinction. It survived by burrowing, but would soon die of starvation.

It marked the end of the Cretaceous Period, and with it the Mesozoic era, while heralding the beginning of the Cenozoic era, which continues to this day.

Conifer

Conifers are a group of cone-bearing seed plants, a subset of gymnosperms.

Conifers are a group of cone-bearing seed plants, a subset of gymnosperms.

The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.
A coniferous forest pictured in the coat of arms of the Kainuu region in Finland
Phylogeny of the Pinophyta based on cladistic analysis of molecular data.
Pinaceae: needle-like leaves and vegetative buds of Coast Douglas fir (Pseudotsuga menziesii var. menziesii)
Araucariaceae: Awl-like leaves of Cook Pine (Araucaria columnaris)
In Abies grandis (grand fir), and many other species with spirally arranged leaves, leaf bases are twisted to flatten their arrangement and maximize light capture.
Cupressaceae: scale leaves of Lawson's Cypress (Chamaecyparis lawsoniana); scale in mm
A thin section showing the internal structure of conifer wood
A Monterey Pine forest in Sydney, Australia
Globosa, a cultivar of Pinus sylvestris, a northern European species, in the North American Red Butte Garden
Pinaceae: unopened female cones of subalpine fir (Abies lasiocarpa)
Taxaceae: the fleshy aril that surrounds each seed in the European Yew (Taxus baccata) is a highly modified seed cone scale
Pinaceae: pollen cone of a Japanese Larch (Larix kaempferi)

Conifers were largely unaffected by the Permian–Triassic extinction event, and were dominant land plants of the Mesozoic era.

First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana.

Tethys Ocean

First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana.
Plate tectonic reconstruction of the Tethys realm at 249 Mya
Plate tectonic reconstruction of the Tethys realm at 100 Mya
Geologist Eduard Suess in 1869

The Tethys Ocean (Τηθύς Tēthús), also called the Tethys Sea or the Neo-Tethys, was an ocean during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents of Gondwana and Laurasia, before the opening of the Indian and Atlantic oceans during the Cretaceous Period.

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Tertiary

Widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.

Widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.

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The Tertiary's time span lies between the Mesozoic and the Quaternary, although no longer recognized as a formal unit by the International Commission on Stratigraphy.

Ichthyosaur

Ichthyosaurs (Ancient Greek for "fish lizard" – ἰχθύς or ichthys meaning "fish" and σαῦρος or sauros meaning "lizard") are large extinct marine reptiles.

Ichthyosaurs (Ancient Greek for "fish lizard" – ἰχθύς or ichthys meaning "fish" and σαῦρος or sauros meaning "lizard") are large extinct marine reptiles.

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The skull found by Joseph Anning in 1811
The torso found by Mary Anning in 1812
Diagram of the skeletal anatomy of Ichthyosaurus communis from an 1824 paper by Conybeare
"Professor Ichthyosaurus" shows his pupils the skull of extinct man, caricature of Charles Lyell by Henry De la Beche (1830)
Hawkins' specimens are still the showpieces of the Natural History Museum
Ichthyosaurus figure at Crystal Palace Park (1854)
Typical Holzmaden fossils: adult and juvenile Stenopterygius quadriscissus
Precious opal replacing ichthyosaur backbone, display specimen, South Australian Museum
Grippia longirostris from the early Triassic of Spitsbergen was already well-adapted to an aquatic lifestyle.
Hupehsuchus
Mixosaurus
Shonisaurus popularis
Stenopterygius resembled a modern dolphin.
Many ichthyosaur lineages continued into the Cretaceous.
Restoration of Platypterygius kiprijanovi – Albian-Cenomanian of Kursk region (Russia)
CGI restoration of Ichthyosaurus communis
Examples of distinct features shared both by dolphins and derived ichthyopterygians
The skull of Temnodontosaurus platyodon has the typical ichthyosaurian shape with an elongated snout and large eye sockets.
Ichthyosaur vertebra from the Sundance Formation (Jurassic) of Natrona County, Wyoming: Note the characteristic hourglass cross-section. (Scale in mm.)
In this specimen seen from below, what looks like a breastbone is in fact the fused coracoids
Ichthyosaur 'paddle' (Charmouth Heritage Coast Centre)
In this arm of Ophthalmosaurus icenius, an additional upper row of elements has developed, ending above in an extra lower arm bone.
A Holzmaden ichthyosaur in which the preparer found organic remains in the position of the dorsal fin, but failed to locate any for the flippers.
An ichthyosaur coprolith
Temnodontosaurus acutirostris with ammonoids
Caypullisaurus is attacked by the crocodylomorph Dakosaurus
Despite their considerable size, the flippers of the Amazon river dolphin are mainly used as rudders.
Temnodontosaurus had the largest eyes of any known vertebrate, indicating a good diving capacity
Chaohusaurus with three juveniles
Detail of a female Stenopterygius with a great number of fetuses in her belly, one of which has been expelled
Life restoration of a female Maiaspondylus giving birth

Ichthyosaurs thrived during much of the Mesozoic era; based on fossil evidence, they first appeared around 250 million years ago (Ma) and at least one species survived until about 90 million years ago, into the Late Cretaceous.

Pterosaur

Pterosaurs ( from Greek pteron and sauros, meaning "wing lizard") were flying reptiles of the extinct clade or order Pterosauria.

Pterosaurs ( from Greek pteron and sauros, meaning "wing lizard") were flying reptiles of the extinct clade or order Pterosauria.

Conical tooth, possibly from Coloborhynchus
Reconstruction of crests: three crested tapegyarids. From top to bottom: Tapejara wellnhoferi, Tupandactylus navigans, Tupandactylus imperator (drawn to scale)
The skull of Thalassodromeus
A neck vertebra of Arambourgiania
The neck of Anhanguera was longer than the torso
The shoulder girdle connected to the notarium
Reconstructed wing planform of Quetzalcoatlus northropi (A) compared to the wandering albatross Diomedea exulans (B) and the Andean condor Vultur gryphus (C). These are not to scale; the wingspan of Q. northropi was more than three times as long as that of the wandering albatross.
Some specimens, such as this Rhamphorhynchus, preserve the membrane structure
Sordes, as depicted here, evidences the possibility that pterosaurs had a cruropatagium – a membrane connecting the legs that, unlike the chiropteran uropatagium, leaves the tail free
An anhanguerid pelvis seen from above, with the right side rotated towards the viewer
Sordes preserved pycnofibers
Jeholopterus
Engraving of the original Pterodactylus antiquus specimen by Egid Verhelst II, 1784
Newman's marsupial pterosaurs
Seeley's dynamical Dimorphodon reconstruction
This drawing of Zhejiangopterus by John Conway exemplifies the "new look" of pterosaurs
The three-dimensionally preserved skull of Anhanguera santanae, from the Santana Formation, Brazil
Life restoration of Sharovipteryx, a gliding "protorosaur" which some controversial studies have posited as a close relative of pterosaurs.
Life restoration of Scleromochlus, an archosauromorph theorized to be related to pterosaurs.
Life restoration of Lagerpeton, lagerpetids share many anatomical and neuroanatomical similarities with pterosaurs.
The skeleton of a pterosaur on display in the Arizona Museum of Natural History in Mesa Arizona.
Diagrams showing breathing motion (top two) and internal air sac system (bottom two)
Pterosaur flight adaptations.
Skeletal reconstruction of a quadrupedally launching Pteranodon longiceps
The probable Azhdarchid trace fossil Haenamichnus uhangriensis.
The fossil trackways show that pterosaurs like Hatzegopteryx were quadrupeds, and some rather efficient terrestrial predators.
Fossil pterodactyloid juvenile from the Solnhofen Limestone
Quetzalcoatlus models in South Bank, created by Mark Witton for the Royal Society's 350th anniversary
Scene from When Dinosaurs Ruled the Earth depicting an outsized Rhamphorhynchus

They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to 66 million years ago ).

Theropoda

Dinosaur clade that is characterized by hollow bones and three-toed limbs.

Dinosaur clade that is characterized by hollow bones and three-toed limbs.

Specimen of the troodontid Jinfengopteryx elegans, with seeds preserved in the stomach region
Fossil of an Anchiornis, showing large preserved feather imprints
Size comparison of selected giant theropod dinosaurs – the largest (left) is Spinosaurus aegyptiacus, smallest (right) is Carcharodontosaurus saharicus.
An ostrich walking on a road in Etosha National Park, Namibia
Mummified enantiornithean wing (of an unknown genus) from Cenomanian amber from Myanmar
Diagram of Deinonychus (left) and Archaeopteryx (right) forelimbs illustrating wing-like posture
Possible early forms Herrerasaurus (large) and Eoraptor (small)
Othniel Charles Marsh, who coined the name Theropoda. Photo c. 1870
Allosaurus was one of the first dinosaurs classified as a theropod.
Ceratosaurus, a ceratosaurid
Irritator, a spinosaurid
Mapusaurus, a carcharodontosaurid
Microraptor, a dromaeosaurid
Passer domesticus, an avian, and the world's most widespread extant wild theropod.

Mesozoic theropods were also very diverse in terms of skin texture and covering.