Arthropod fossils are concurrent with the earliest plant fossils of the Silurian. Millipedes, centipedes and arachnids continued to diversify during the Devonian Period. The earliest known insect, Rhyniella praecusor, was a flightless hexapod with antennae and a segmented body. Fossil Rhyniella are between 412 million and 391 million years old.
Early tetrapods probably evolved from Lobe-finned fishes able to use their muscular fins to take advantage of the predator-free and food-rich environment of the new wetland ecosystems. The earliest known tetrapod is Tiktaalik rosae. Dated from the mid-Devonian, this fossil creature is considered to be the link between the lobe-finned fishes and early amphibians. Tiktaalik was probably mostly aquatic, “walking” on the bottom of shallow water estuaries. It had a fish-like pelvis, but its hind limbs were larger and stronger than those in front, suggesting it was able to propel itself outside of an aquatic environment. It had a crocodile-like head, a moveable neck, and nostrils for breathing air.
Early tetrapods probably evolved from Lobe-finned fishes able to use their muscular fins to take advantage of the predator-free and food-rich environment of the new wetland ecosystems. The earliest known tetrapod is Tiktaalik rosae. Dated from the mid-Devonian, this fossil creature is considered to be the link between the lobe-finned fishes and early amphibians. Tiktaalik was probably mostly aquatic, “walking” on the bottom of shallow water estuaries. It had a fish-like pelvis, but its hind limbs were larger and stronger than those in front, suggesting it was able to propel itself outside of an aquatic environment. It had a crocodile-like head, a moveable neck, and nostrils for breathing air.
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