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Terrestrial
Animal Life and Evolution of Herbivores
The most important terrestrial herbivores
in the Early Permian were the insects. They represented a mixture
of holdovers from the earlier Pennsylvanian, such as the dragonfly-like
palaeodictyopterans and various forms related to modern grasshoppers
and cockroaches, as well as newly evolved forms such as beetles
and scorpionflies that are the earliest known members of insect
groups that undergo true metamorphosis. (Insects that metamorphose
develop from egg to larva to pupa to adult, and generally make their
living in a very different way in the larval and adult phases.)
The advent of insects that could metamorphose had a profound effect
on the ecology and evolution of insects, because immature life stages
could use different resources than adults of the same species. Evidence
for these new herbivores is seen in Permian plant fossils with new
types of damage to leaves and seeds. Sedimentary rocks of Permian
age also reveal fossil burrows made by the first insects to colonize
quiet-water aquatic ecosystems.
The Permian terrestrial world hosted representatives of most major
groups of vertebrates, although many appeared quite different from
their modern relatives. A great diversity of amphibians lived on
land and in nearby fresh water, including giant temnospondyl
carnivores (Eryops), large herbivores (Diadectes),
and many reptile-like forms (Seymouria and Limnoscelis).
The two major groups of early amniotes, the
synapsids
(often called mammal-like reptiles) and true reptiles
(diapsids and
anapsids), had by
now diversified into many different types. Some diapsids, such as
the semiaquatic Youngina and the gliding Coelurosauravus,
show very unusual adaptations. Armored pareiasaurs
were some of the world’s first large vertebrate herbivores.
Early synapsids (pelycosaurs) were more abundant
than early diapsids. Many of the first large herbivores were
pelycosaurs, such as
caseids and the
sail-backed Edaphosaurus. Carnivorous forms were even more common, ranging from small
varanopseids to the large Dimetrodon
and Sphenacodon. Later in the Permian, more advanced forms evolved, such as the smaller and more mammal-like
therapsids. Diverse therapsids are especially
known from Russia and South Africa, including heavy-headed dinocephalians and
gorgonopsians, rodent-like theriodonts, and
cow-like herbivorous dicynodonts.
Although carnivorous animals radiated throughout the Permian, herbivory
was probably the most noteworthy vertebrate adaptation. Herbivores
require a suite of characteristics to effectively process plant
material, which is often indigestible to vertebrates. These include
varied tooth shapes that allow animals to crop and chew plants.
These teeth often show well-developed occlusal (contact) surfaces
that indicate food was being ground down in the mouth. In addition,
vertebrate herbivores tend to be large, with spacious guts to process
large amounts of plant materials. All of these features are seen
in the vertebrate herbivores of the Permian. |
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Overview |
Terrestrial Animal Life and Evolution of Herbivores |
Permian Terrestrial Floras
The Marine Realm and The End-Permian Extinction |
Tectonics, Climate, and the Formation of Pangea
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