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Animals in the Carboniferous Period

The Carboniferous Period spanned a portion of the Paleozoic Era from 354 to 290 million years ago. The period took its name from the seams of coal that its flora produced. Large oceans harbored abundant sea life. The Carboniferous followed the Devonian Period, the "Age of Fishes," and most of Earth's animal biomass remained in the sea. Geologists divide the period into the earlier Mississippian and later Pennsylvanian subperiods based on stratigraphic differences.

Sharks
- Sharks cruised Carboniferous seas in search of a meal much as they do today.
  
  Although sharks first made an appearance in the fossil record during the Silurian Period around 415 million years ago, they proliferated during the Carboniferous Period. Scientists colloquially refer to the period as the "Golden Age of Sharks." While other Devonian species suffered extinctions, sharks, skates and rays took advantage of the newly opened spaces in the food web and flourished. Modern sharks still closely resemble their Carboniferous forebears.
Aquatic Invertebrates
- Aquatic trilobites thrived in Carboniferous seas.
  
  A host of marine life filled the shallow seas of the period. Crinoids, flower-shaped sessile animals, filtered their food from the rich waters of Carboniferous tidal pools and seas. Mollusks began to move into freshwater environments, while gastropods made their way onto land. Trilobites left an extensive fossil record, but these alien-looking creatures no longer swim in Earth's seas. The sea sponges that extend into virtually every ocean on Earth made their first appearance during the Carboniferous Period.
Terrestrial Arthropods
- Modern scorpions are tiny compared to their Carboniferous ancestors.
  
  Abundant plant life created the oxygen-rich atmosphere of the Carboniferous Period. Insects lacked lungs then as they do now, relying instead on passive air movement through small openings in their exoskeletons to oxygenate their tissues. More oxygen in the air meant considerably larger insects. Dragonfly-like insects with 30-inch wingspans and relatives of millipedes that grew to 2 yards long roamed through Carboniferous fern forests. Immense scorpions over a yard long shared the forest with them. Mayflies and cockroaches make their first appearance during this time.
Amphibians
- Newts resemble their forebears, but are much smaller in the modern era.
  
  Vertebrate animal life still stayed near the water from which it came throughout the Carboniferous Period; not until the Permian Period did the "Age of Amphibians" occur. Amphibians respire through their skin as well as with their lungs, so like arthropods, they grew large in the oxygen-rich atmosphere. The largest Carboniferous amphibians grew as large as modern alligators.
Reptiles
- The scaly skin of reptiles helped them weather climate changes.
  
  While amphibians and their soft, unshelled eggs required water to breed, reptiles could travel farther from shorelines and face less competition. Their eggs could withstand the relatively more arid inland environments. Reptiles' dry, scaly skins also helped protect them from harsher surroundings and, during the later Carboniferous Period, from predators as scales became more like armor. Around 300 million years ago, an unknown major event caused extensive rain-forest collapse; amphibians' development slowed during this time of relative cool and arid weather, but reptiles thrived.

Nature