Context: The earliest clear evidence of hair or fur is in fossils of Castorocauda, from 164 million years ago in the Middle Jurassic. In the 1950s, it was suggested that the foramina (passages) in the maxillae and premaxillae (bones in the front of the upper jaw) of cynodonts were channels which supplied blood vessels and nerves to vibrissae (whiskers) and so were evidence of hair or fur; it was soon pointed out, however, that foramina do not necessarily show that an animal had vibrissae, as the modern lizard Tupinambis has foramina that are almost identical to those found in the nonmammalian cynodont Thrinaxodon. Popular sources, nevertheless, continue to attribute whiskers to Thrinaxodon.

Question: When is it believed that the earliest know hair was said to exist?
Answer: 164 million years ago

Question: When was it suggested that foramina premaxillae could contain the first know hairs?
Answer: 1950s

Question: Which major time period were these suggested hairs from?
Answer: Jurassic

Question: What type of fossils showed the earliest evidence of cynodonts?
Answer: Unanswerable

Question: What was suggested about the Tupinambis in the Thrinaxodon in the 1950's?
Answer: Unanswerable

Question: What do popular sources attribute foramina to?
Answer: Unanswerable

Question: At what time is it believed the earliest known foramina existed?
Answer: Unanswerable

Question: What does the modern lizard Castorocauda have?
Answer: Unanswerable