Final answer:
During the Late Paleozoic, amphibians and the early reptiles (amniotes) were significant. Amphibians were the first vertebrates to live on land and thrived during this era, while the reptiles laid terrestrial eggs and diversified into various lineages.
Step-by-step explanation:
The Late Paleozoic Era, specifically the Carboniferous and Permian periods, was a pivotal time in the history of life on Earth. During this era, various animals made significant evolutionary strides. Among the major groups of animals that thrived during the Late Paleozoic were the amphibians and the early reptiles, known as amniotes. Both groups are important for their unique contributions to vertebrate evolution.
Amphibians, such as salamanders, frogs, and caecilians, were the first vertebrates to conquer the land. The widespread distribution of tetrapods during the early Carboniferous period led to it being called the "age of the amphibians." These animals typically underwent a two-stage development process, including a gilled aquatic larval stage and a terrestrial adult stage. The reptiles, on the other hand, are part of the amniotes, which laid eggs that were well-adapted to terrestrial environments, allowing them to reproduce on land effectively.
The diversification of vertebrates during the Late Paleozoic also saw the rise of invertebrates such as worms and insects, which, along with amphibians and reptiles, contributed to the evolving ecosystems. Thus, while amphibians were certainly a significant group during the Late Paleozoic, reptiles started to emerge as another influential group, leading to a split in evolutionary lines that gave rise to distinct lineages like synapsids and sauropsids.