Pangea Rodinia and Gondwanaland: species and there origins on ancient continents

Siluruian and Devonian:

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5Mya (million years ago), to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya (ICS, 2004,^[5] chart). As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a major extinction event when 60% of marine species were wiped out. See Ordovician-Silurian extinction events.

Silurian Period

443.7 – 416 million years ago

PreЄ

Silurian Period

443.7 – 416 million years ago

Permian-Triassic

Mean atmospheric O₂content over period duration

Mean atmospheric CO₂content over period duration

Mean surface temperature over period duration

Sea level (above present day)

ca. 14 Vol %^[1]

(70 % of modern level)

ca. 4500 ppm^[2]

(16 times pre-industrial level)

ca. 17 °C^[3]

(3 °C above modern level)

Around 180m, with short-term negative excursions^[4]

Devonian Period

416 – 359.2 million years ago

PreЄ

Mean atmosphericO₂ content over period duration

Mean atmosphericCO₂ content over period duration

Mean surface temperature over period duration

Sea level (above present day)

ca. 15 Vol %^[1]

(75 % of modern level)

ca. 2200 ppm^[2]

(8 times pre-industrial level)

ca. 20 °C^[3]

(6 °C above modern level)

Relatively steady around 180m, gradually falling to 120m through period^[4]

Early Eocene 50-35 Ma

The Devonian is a geologic period and system of the Paleozoic Era spanning from 416 to 359.2 million years ago(ICS, 2004,^[5] chart). It is named after Devon, England, where rocks from this period were first studied.

During the Devonian Period the pectoral and pelvic fins of lobe-finned fish evolved into legs^[6] as they started to walk onland as tetrapods around 397 Ma.^[7] Various terrestrial arthropods also became well-established.

The first seed-bearing plants spread across dry land, forming huge forests. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician, and the first ray finned and lobe-finned bony fish evolved. The first ammonite mollusks appeared, and trilobites, the mollusc-like brachiopods, as well as great coral reefs were still common. The Late Devonian extinction severely affected marine life.

The paleogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, and the early formation of the small supercontinent of Euramerica in between.