Which animals came first? For more than a century, most evidence suggested that sponges, immobile filter-feeders that lack muscles, neurons and other specialized tissues, were the first animal ...

For more than a century, biologists have wondered what the earliest animals were like when they first arose in the ancient oceans over half a billion years ago. Searching among today's most ...

For almost two decades, scientists have debated whether sponges or comb jellies are the first animal lineage. Now some are calling for a more harmonious approach. Which animals came first? For more ...