The terrestrial animal radiations that
had started in the Mississippian continued into the Pennsylvanian.
The great coal forests housed enormous insects such
as dragonflies (Meganeura) with up to 70-centimeter
wingspans, paleodictyopterans with 55-centimeter wingspans, and a
variety of large protorthopterans and cockroaches.
Other giant terrestrial arthropods included large spider-like animals
and a two-meter-long relative of millipedes called Arthropleura.
Some of the giant arthropods were early terrestrial herbivores,
such as paleodictyopterans with mouthparts adapted for piercing and
sucking the juices out of plants, and protorthopterans with chewing
mouthparts. These herbivorous insects became food for predaceous arthropods
like the dragonflies and scorpions, as well as for early tetrapods.
These tetrapods were carnivores (sometimes cannibals)
as well as insectivores, but none had yet mastered
herbivory. Early amphibians included reptile-like anthracosaurs, snake-like
aïstopods, and eel-like semiaquatic forms.
Although amniotes may have evolved as early as the Mississippian,
the oldest definitively known amniote fossil is from the Middle
Pennsylvanian of Joggins, Nova Scotia. These early "reptilian" skeletal fossils belong to genera such as Hylonomus and Palaeothyris. During the Pennsylvanian,
primitive amniotes were able to diversify as they occupied many
terrestrial niches and acquired new ecological roles. These primitive amniotes quickly diverged into
synapsids (later to include
diapsids (which would include
birds, lizards, and snakes). These two groups represent nearly all
amniotes on Earth today. In addition, more primitive forms called parareptiles appeared as well.
Pennsylvanian Animal Life |
Plant Life and the Coal Forests
Pennsylvanian Climate and Tectonics
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