Kimmeridgian in the context of "Tithonian"

Diplodocus (/dɪˈplɒdəkəs/, /daɪˈplɒdəkəs/, or /ˌdɪploʊˈdoʊkəs/) is an extinct genus of diplodocid sauropod dinosaurs known from the Late Jurassic of North America. The first fossils of Diplodocus were discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique.

The genus lived in what is now mid-western North America, at the end of the Jurassic period. It is one of the more common dinosaur fossils found in the middle to upper Morrison Formation, with most specimens being found in rocks dated between about 151.88 and 149.1 million years ago, during the latest Kimmeridgian Age, although it may have made it into the Tithonian, with at least one specimen (AMNH FR 223) being potentially from among the youngest deposits of the formation. The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs, such as Apatosaurus, Barosaurus, Brachiosaurus, Brontosaurus, and Camarasaurus. Its great size may have been a deterrent to the predators Allosaurus and Ceratosaurus: their remains have been found in the same strata, which suggests that they coexisted with Diplodocus.

Apatosaurus (/əˌpætəˈsɔːrəs/; meaning "deceptive lizard") is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, Apatosaurus ajax, in 1877, and a second species, Apatosaurus louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t (16.1–22.0 long tons; 18.1–24.7 short tons). A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t (32 long tons; 36 short tons).

The cervical vertebrae of Apatosaurus are less elongated and more heavily constructed than those of Diplodocus, a diplodocid like Apatosaurus, and the bones of the leg are much stockier despite being longer, implying that Apatosaurus was a more robust animal. The tail was held above the ground during normal locomotion. Apatosaurus had a single claw on each forelimb and three on each hindlimb. The Apatosaurus skull, long thought to be similar to Camarasaurus, is much more similar to that of Diplodocus. Apatosaurus was a generalized browser that likely held its head elevated. To lighten its vertebrae, Apatosaurus had air sacs that made the bones internally full of holes. Like that of other diplodocids, its tail may have been used as a whip to create loud noises, or, as more recently suggested, as a sensory organ.

Brontosaurus (/ˌbrɒntəˈsɔːrəs/; meaning "thunder lizard" from the Greek words βροντή, brontē "thunder" and σαῦρος, sauros "lizard") is a genus of herbivorous sauropod dinosaur that lived in present-day United States during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed B. excelsus, based on a partial skeleton lacking a skull found in Como Bluff, Wyoming. In subsequent years, two more species of Brontosaurus were named: B. parvus in 1902 and B. yahnahpin in 1994. Brontosaurus lived about 156 to 146 million years ago (mya) during the Kimmeridgian and Tithonian ages in the Morrison Formation of what is now Utah and Wyoming. For decades, the animal was thought to have been a taxonomic synonym of its close relative Apatosaurus, but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct. It has seen widespread representation in popular culture, being the archetypal "long-necked" dinosaur in general media.

The anatomy of Brontosaurus is well known, with fossils demonstrating that it was large, long-necked, and quadrupedal with a long tail terminating in a whip-like structure. The cervical vertebrae are notably extremely robust and heavily built, in contrast to its lightly built relatives Diplodocus and Barosaurus. The forelimbs were short and stout whereas the hindlimbs were elongated and thick, supported respectively by a heavily built shoulder girdle and pelvis. Several size estimates have been made, with the largest species B. excelsus reaching up to 21–23 m (69–75 ft) from head to tail and weighing in at 15–20 t (17–22 short tons), whereas the smaller B. parvus only got up to 19 m (62 ft) long. Juvenile specimens of Brontosaurus are known, with younger individuals growing rapidly to adult size in as little as 15 years.

Camarasaurus (/ˌkæmərəˈsɔːrəs/ KAM-ər-ə-SOR-əs) is a genus of sauropod dinosaur that lived in North America during the Late Jurassic epoch. Its fossil remains have been found in the Morrison Formation, dating to the Kimmeridgian and Tithonian ages of the Jurassic, between 155 and 145 million years ago (mya).

Camarasaurus presented a distinctive cranial profile of a blunt snout and an arched skull that was remarkably square, typical of basal macronarians. The generic name means "chambered lizard", referring to the hollow chambers, known as pleurocoels, in its cervical vertebrae (Greek καμαρα [kamara] meaning 'vaulted chamber', or anything with an arched cover, and σαυρος [sauros] meaning 'lizard').

Allosaurus (/ˌæləˈsɔːrəs/ AL-o-SAWR-us) is a genus of theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period (Kimmeridgian to late Tithonian ages). The first fossil remains that could definitively be ascribed to this genus were described in 1877 by Othniel C. Marsh. The name "Allosaurus" means "different lizard", alluding to its lightweight vertebrae, which Marsh believed were unique. The genus has a very complicated taxonomy and includes at least three valid species, the best known of which is A. fragilis. The bulk of Allosaurus remains come from North America's Morrison Formation, with material also known from the Alcobaça, Bombarral, and Lourinhã formations in Portugal. It was known for over half of the 20th century as Antrodemus, but a study of the abundant remains from the Cleveland-Lloyd Dinosaur Quarry returned the name "Allosaurus" to prominence. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles.

Allosaurus was a large bipedal predator for its time. Its skull was light, robust, and equipped with dozens of sharp, serrated teeth. It averaged 8.5 meters (28 ft) in length for A. fragilis, with the largest specimens estimated as being 9.7 meters (32 ft) long. Relative to the large and powerful legs, its three-fingered hands were small and the body was balanced by a long, muscular tail. It is classified in the family Allosauridae. As the most abundant large predator of the Morrison Formation, Allosaurus was at the top of the food chain and probably preyed on large herbivorous dinosaurs such as ornithopods, stegosaurids, and sauropods. Scientists have debated whether Allosaurus had cooperative social behavior and hunted in packs or was a solitary predator that forms congregations, with evidence supporting either side.

The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic Epoch, or the lowest stage of the Upper Jurassic Series. It spans the time between 161.5 ± 1.0 Ma and 154.8 ± 0.8 Ma (million years ago). The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian.

Stegosaurus (/ˌstɛɡəˈsɔːrəs/; lit. 'roof-lizard') is a genus of herbivorous four-legged armored dinosaurs from the Late Jurassic, characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails. Fossils of the genus have been found in the western United States and in Portugal, where they are found in Kimmeridgian- to Tithonian-aged strata, dating to between 155 and 145 million years ago. Of the species that have been classified in the upper Morrison Formation of the western US, only three are universally recognized: S. stenops, S. ungulatus and S. sulcatus. The remains of over 80 individual animals of this genus have been found. Stegosaurus would have lived alongside dinosaurs such as Apatosaurus, Diplodocus, Camarasaurus and Allosaurus, the latter of which may have preyed on it.

They were large, heavily built, herbivorous quadrupeds with rounded backs, short fore limbs, long hind limbs, and tails held high in the air. Due to their distinctive combination of broad, upright plates and tail tipped with spikes, Stegosaurus is one of the most recognizable kinds of dinosaurs. The function of this array of plates and spikes has been the subject of much speculation among scientists. Today, it is generally agreed that their spiked tails were most likely used for defense against predators, while their plates may have been used primarily for display, and secondarily for thermoregulatory functions. Stegosaurus had a relatively low brain-to-body mass ratio. It had a short neck and a small head, meaning it most likely ate low-lying bushes and shrubs. One species, Stegosaurus ungulatus, is one of the largest known of all the stegosaurians, with the largest known specimens measuring about 7.5 metres (25 ft) long and weighing over 5 metric tons (5.5 short tons).