Encyclopedia of Evolution.pdf - Online Reading Center

Marine life. All modern groups of marine organisms
existed during the Carboniferous, except aquatic mammals.
Many older lineages of fishes, such as the armored fishes of
the preceding Devonian period, became extinct, while the
fish lineages that are dominant today proliferated (see fishes,
evolution of).
Life on land. Extensive swamps filled the shallow seas
and lakes of the Carboniferous period in the tropical areas.
Plant and animal life included:
• Plants. Large trees had been rare in the Devonian period,
but trees up to 100 feet (30 m) in height became abundant
in the Carboniferous. Most of these were tree-sized versions
of modern club mosses and horsetails (see seedless
plants, evolution of). These trees had systems of water
transport and sexual reproduction that would not work
very well for tree-sized plants on the Earth today but functioned
well in the very wet conditions of the Carboniferous.
The first seed plants evolved, possibly in drier upland
regions, during this time (see gymnosperms, evolution
of). The seed plants became more common, and the seedless
trees began their slide toward extinction, during a period
of drier weather during the Carboniferous. Some seed
plants, such as the seed ferns, were in evolutionary lineages
that are now extinct. There were no flowering plants.
• Animals. Insect groups such as dragonflies and beetles were
abundant during this period. Many of them, particularly
dragonflies, were larger than any insects now alive on the
Earth. Insects breathe through openings along their abdomens,
which is an efficient method of gas exchange only in
small animals or under conditions of elevated oxygen concentration.
The large size of some Carboniferous insects has
suggested to some paleontologists that the amount of oxygen
in the atmosphere greatly exceeded that of today. The
insects were predators or ate plant spores; herbivores, that
ate leaf material, were apparently very rare. The shortage of
herbivores may have contributed to the great accumulation
of plant material into what became coal. Amphibians had
evolved during the preceding Devonian period (see amphibians,
evolution of) and proliferated during the Carboniferous
into many forms, some large. The first vertebrates with
hard-shelled eggs, which would today be classified as reptiles,
evolved during the Carboniferous period (see reptiles, evolution
of). Although some reptile lineages are not known
until the Permian period, all of the major reptile lineages had
probably separated before the end of the Carboniferous period.
There were not yet any dinosaurs, mammals, or birds.
Extinctions. The Carboniferous period is not recognized
to contain one of the major extinction events. A worldwide
period of warmer, drier climate near the end of the Carboniferous
created conditions that favored the spread and diversification
of seed plants and reptiles.
Further Reading
White, Toby, Renato Santos, et al. “The Carboniferous.” Available
online. URL: http://www.palaeos.com/Paleozoic/Carboniferous/
Carboniferous.htm. Accessed March 23, 2005.
catastrophism
catastrophism Catastrophism was a set of geological theories
that claimed that Earth history was dominated by a series
of worldwide catastrophes. This approach dominated geology
through the early 19th century, before uniformitarianism
gained prominence (see Hutton, James; Lyell, Charles).
Catastrophists, among whom Georges Cuvier in France
and William Buckland in England figured prominently (see
Cuvier, Georges), believed that the Earth’s geological history
was divided into a series of ages, separated by spectacular
worldwide catastrophes. They believed that the Flood of Noah
was the most recent of these catastrophes. Some modern creationists
have called themselves catastrophists. They attribute
all of the geological deposits to the Flood of Noah, on an Earth
recently created. However, this position was not held among
catastrophist geologists of the 19th century. It is primarily a
product of 20th-century fundamentalism (see creationism).
In studying the geological deposits of the Paris Basin,
Cuvier determined that the Earth had experienced a long
history, with many ages previous to this one. He found skeletons
of mammals of kinds that no longer exist, from terrestrial
deposits, with oceanic deposits over them; to him this
meant that a catastrophic flood had destroyed the world in
which those mammals lived. Each previous age of the Earth
was destroyed by a flood, then repopulated with plants and
animals created anew by the Creator. Each time, the world
became more and more suitable for human habitation, which
Cuvier thought was the Creator’s ultimate goal. The last
of the floods, the Flood of Noah, was so sudden as to have
left mammoths, hair and all, frozen in ice. As a result of the
research of Louis Agassiz (see Agassiz, Louis), geologists
had to admit that this most recent supposed flood was actually
an ice age, in which glaciers, not floodwaters, had piled
up moraines of rubble (see ice ages).
Prior to the 19th century division between catastrophists
and uniformitarians, the 18th century had been dominated
by the Plutonists and the Neptunists. The Plutonists claimed
that the geological history of the Earth had been dominated
by volcanic eruptions and earthquakes. The Neptunists, in
contrast, emphasized the role of worldwide floods. The Plutonists
demanded to know, where did the water go after
worldwide floods? The Neptunists demanded to know, without
worldwide floods, how did fossilized seashells end up on
mountaintops? Nineteenth-century catastrophists accepted
both volcanic and flood processes, while uniformitarians
rejected the worldwide effects of both processes. None of
them suspected that the continents might actually move (see
continental drift).
The teleological and supernaturalistic approach of catastrophism
had to give way to Lyell’s scientific approach in
order for progress to continue in geological sciences. Cuvier
was not totally wrong nor Lyell totally right. The catastrophists
believed in an Earth in which biological progress
occurred, while Lyell believed in uniformity of state; the
former approach opens the way to evolutionary science.
Catastrophists, furthermore, realized that there were abrupt
transitions between one geological age and another, while
Lyell believed in uniformity of rate; the former approach