The order is thought to have first diverged from other related monocots some 120-130 million years ago ( early in the Cretaceous period ), although given the difficulty in classifying the families involved, estimates are likely to be uncertain.

The Asterales order probably originated in the Cretaceous ( 145 – 65 Mya ) on the supercontinent Gondwana which broke up from 184 – 80 Mya, forming the area that is now Australia, South America, Africa, India and Antarctica.

Albertosaurus (; meaning " Alberta lizard ") is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, about 70 million years ago.

Amber is globally distributed, mainly in rocks of Cretaceous age or younger.

Its chemical composition makes it difficult to match the amber to its producers – it is most similar to the resins produced by flowering plants ; however, there are no flowering plant fossils until the Cretaceous, and they were not common until the Upper Cretaceous.

Amber becomes abundant long after the Carboniferous, in the Early Cretaceous,, when it is found in association with insects.

A classic example of this is the replacement of the non-avian dinosaurs with mammals at the end of the Cretaceous, and of brachiopods by bivalves at the Permo-Triassic boundary.

The Cretaceous (, ), derived from the Latin " creta " ( chalk ), usually abbreviated K for its German translation Kreide ( chalk ), is a geologic period and system from circa to million years ( Ma ) ago.

In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the Cenozoic era.

The end of the Cretaceous is defined by the K – Pg boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic Eras.

In older literature the Cretaceous is sometimes divided into three series: Neocomian ( lower / early ), Gallic ( middle ) and Senonian ( upper / late ).

The Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the Cretaceous system consists for a major part of marine limestone, a rock type that is formed under warm, shallow marine circumstances.

Chalk is a rock type characteristic for ( but not restricted to ) the Cretaceous.

In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls.

The Cretaceous is justly famous for its chalk ; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic.

In the area that is now India, massive lava beds called the Deccan Traps were erupted in the very late Cretaceous and early Paleocene.

Rafting by ice of stones into marine environments occurred during much of the Cretaceous but evidence of deposition directly from glaciers is limited to the Early Cretaceous of the Eromanga Basin in southern Australia.

File: Triceratops BW. jpg | Triceratops is one of the most recognizable genera of the Cretaceous.

In the middle and late Cretaceous Period, about 100 million years ago, the San Luis Valley lay on the shore of or beneath the Western Interior Seaway a shallow sea which divided North America into two parts.

The Late Cretaceous ( 100. 5 – 66 Ma ) is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale.

The most extensive non-marine formations were deposited in the Cretaceous period when the eastern part of the Cretaceous Seaway ( a warm shallow sea that periodically divided North America in that period ) covered the region.

Large parts of previously deposited formations were removed ; probably by streams that washed the sediment into the Cretaceous Seaway that longitudinally divided North America to the east.

During the Cretaceous, the late-Paleozoic-to-early-Mesozoic supercontinent of Pangaea completed its tectonic breakup into present day continents, although their positions were substantially different at the time.

Additionally, all six turtle families in existence at the end of the Cretaceous survived into the Tertiary and are represented by current species.

The order Squamata, which is represented today by lizards, snakes, and amphisbaenians, radiated into various ecological niches during the Jurassic and were successful throughout the Cretaceous.

Australia-New Guinea, having split from Gondwana during the early Cretaceous, drifted north and, eventually, collided with South-east Asia ; Antarctica moved into its current position over the South Pole ; the Atlantic Ocean widened and, later in the era, South America became attached to North America.

The era is subdivided into three major periods: the Triassic, Jurassic, and Cretaceous, which are further subdivided into a number of epochs and stages.

Lasting 42 million years, the Paleogene is most notable as being the time in which mammals evolved from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous – Paleogene extinction event that ended the preceding Cretaceous Period.

After the Cretaceous – Paleogene extinction event, which saw the demise of the dinosaurs, they transformed from a few small and generalized forms and began to evolve into most of the modern varieties we see today.

Fossil records indicate that Procellariiformes have been around at least 60 million years, but a DNA-based study from 1997 states that they have been around into the Cretaceous Period and survived the Cretaceous – Paleogene extinction event.

The euechinoids, on the other hand, diversified into new lineages throughout the Jurassic and into the Cretaceous periods, and from them emerged the first irregular echinoids ( superorder Atelostomata ) during the early Jurassic, and later the other superorder ( Gnathostomata ) of irregular urchins, which evolved independently.

The Treatise on Invertebrate Paleontology ( Part L, 1957 ) divides the Ammonoidea, regarded simply as an order, into eight suborders, the Anarcestina, Clymeniina, Goniatitina, and Prolecanitina from the Paleozoic ; the Ceratitina from the Triassic ; and the Ammonitina, Lytoceratina, and Phylloceratina from the Jurassic and Cretaceous.

Six other families made it well into the upper Maastrichtian ( uppermost stage of the Cretaceous ) but were extinct well before the end.

The archipelago itself ( produced by the Pacific plate moving over a hot spot ) has existed for far longer, at least into the Cretaceous.

From the Early Cretaceous and into Late Cretaceous times the Harz was uplifted in a single block by tectonic movements and, particularly during the Tertiary period, the younger overlying strata were eroded and the underlying base rock left standing as low mountains.

Early marsupial mammals evolved in the Early Cretaceous, with true placentals emerging in the Late Cretaceous period.

The Liaoning lagerstätte ( Chaomidianzi formation ) in China provides a glimpse of life in the Early Cretaceous, where preserved remains of numerous types of small dinosaurs, birds, and mammals have been found.

It is estimated that Dioscoreales and its sister clade Pandanales split up around 121 millions of years ago during Early Cretaceous when the stem group was formed.

It lived during the Early Cretaceous, in China, where the first fossil was found in the Junggar Basin.

Fossilized worms have been reported from Early Cretaceous Burmese amber dated to 100 – 110 million years.

Fossil mackerel shark teeth date to the Early Cretaceous.

The fossil record shows that monotremes have been present in Australia since the Early Cretaceous 145 – 99 MYA, and that marsupials and placental mammals date from the Eocene 56 – 34 MYA, when modern mammals first appeared in the fossil record.

* Crioceratites elegans, an ammonite species from the Early Cretaceous

In particular Enaliornis, which was apparently an ancestral and plesiomorphic member of that order, was sometimes used to support claims of Albian ( Early Cretaceous ) Gaviiformes.

Not all reefs in the past were formed by corals: those in the Early Cambrian ( 542 – 513 Ma ) resulted from calcareous algae and archaeocyathids ( small animals with conical shape, probably related to sponges ) and in the Late Cretaceous ( 100 – 65 Ma ), when there also existed reefs formed by a group of bivalves called rudists ; one of the valves formed the main conical structure and the other, much smaller valve acted as a cap.

The Early Cretaceous ( Berriasian, around 143 mya ) genus Eurolimnornis from NW Romania was initially believed to be a grebe.

For example, the dentition of the Early Cretaceous monotreme Steropodon is similar to those of Peramus and dryolestoids, which suggests that monotremes are related to some pre-tribosphenic therian mammals, but, on the other hand, the status of neither of these two groups is well-established.

Thus, ocean currents at that time — around the Early Cretaceous — ran radically differently from the way they do today.

At Gantheaume Point and out to sea are dinosaur footprints dated as Early Cretaceous in age ( approximately 130 million years ago ).