2. Paleocene Climate, Geography & Life

Paleocene Climate

During the Paleocene the earth’s climate regime was much warmer than it is today, by as much as 15°C (27°F) and atmospheric concentrations of CO2 were at around 500 ppm. Though several regions were arid, tropical and sub tropical forests extended further north than today, whilst warm temperate forests and cool temperate plants extended further north still. Ice ages have occurred only in four distinct periods during earth’s history; at the time of the Paleocene there hadn’t been an ice age for around 100 million years.

See also: Why Earth’s Climate Is Different Today


Paleocene Geography

At the time of the Paleocene the shapes of the continents were similar to those of today, but they were in different positions on the globe due to the movements of tectonic plates. During the Cretaceous period North America, Greenland and Eurasia had together formed a northern super-continent called Laurasia, but at the end of the Paleocone North America and Greenland began to separate from Eurasia; this opened the northeast Atlantic.

At this time the distance between Europe and Greenland was just one tenth of what it is today. This separation was initiated by volcanic activity, deep under the earth’s crust, causing rifting, thinning and spreading of the sea floor that moved the two continental plates apart. This resulted in massive, periodic volcanic activity in the area between Baffin Island and northwest Europe that later created several islands in the North Atlantic and extended as far south as the Bristol Channel. Map of: Laurasia, America And The NE Atlantic In The Early Paleocene. From: MantlePlumes dot org.

Britain, Ireland and Norway were all landlocked and part of western Laurasia whilst Iceland, though an undersea volcanic hot spot, would not become an island for another 35 million years. The Arctic sea was almost completely surrounded by land and much less salty than today, a land bridge joined Scotland to Greenland and Canada whilst another connected Siberia with Alaska.

We would be unable to recognise many of today’s familiar features; several shallow seas covered large areas of the continents e.g. most of central Asia, whilst mountain ranges such as the Alps and Himalayas were formed only later in the Tertiary period. 

Following the break-up of a southern super-continent called Gondwana Africa was then an island, further south than it is today, separated from Eurasa by the Tethys Seaway.

India had detached from East Africa and would begin its collision with Asia during the Eocene around 50 mya.

Australia and New Guinnea had only recently separated from Antarctica and begun a slow drift northwards, though Tasmania would remain connected to Antarctica for another five million years.

South America remained connected to Antartica until 40 mya, when it began its drift north to collide with the Caribbean Plate around 10 mya; this caused the uplift of the Isthmus of Panama that would divide the Atlantic from the Pacific 3.5 mya.

Map: Position Of Continents At Time Of Paleocene. University Of Maryland.


Paleocene Life

Prior to the PETM non-avian dinosaurs had been extinct for some ten million years and early mammals (including some primates) were the dominant forms of life, along with amphibians, reptiles, insects and flowering plants. These mammals are considered ‘primitive’ as they had a less sophisticated anatomy in comparison to the mammals that appeared after the PETM. e.g. many had yet to develop specialisations such as teeth suited to one particular type of food or legs developed for speed.

Most animals were insectivores or omnivores, though both true herbivores and carnivores were starting to appear. The main carnivorous predators were species that had survived the extinction event at the end of the Cretaceous, such as early crocodiles and sharks.

The Paleocene mammals were generally small, short-legged, walked on the soles of their feet and had five toes on each foot. A larger diversity of animals was fond in Laurasia than North America had so far been able to support, this would dramatically change as a result of the PETM.

Find out more:

Paleocene Mammals (PowerPoint Presentation).

Introduction To Paleocene Mammals. Index Page.

More Paleocene Mammal Links

Climate

Why Earth’s Climate Has Changed in The Past 60 Million Years. University of Maine.

The Uplift-Weathering Hypothesis. (Raymo & Ruddiman. 1992.) General overview.

The Carbon Cycle and Earth's Climate.

When Have Ice Ages Occurred?

Milankovitch Cycles

Paleoclimatology

 

Paleocene-Eocene

Thermal Maximum

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