This article was first published in the July 2006 ABR Electronic Newsletter.
Recently, much has been made of a fossil discovered in Arctic Canada that is being touted as an unmistakable evolutionary link between fish and land animals. In 2004, Farish Jenkins, Alexander Agassiz Professor of Zoology and curator of vertebrate paleontology at Harvard, along with colleagues from the Academy of Natural Sciences of Philadelphia and the University of Chicago, unearthed this fossil near Bird Fiord on Ellesmere Island not far from the North Pole.
Given the scientific name Tiktaalik roseae, the creature had gills and scales like a fish, but an elongated snout and flattened head like a crocodile’s. It also had a neck, unlike other fish, a trait that allowed it to move its head independently. It had eyes on the top of its head, like modern-day surface-dwelling creatures such as frogs, crocodiles, and mudskippers. Its stout skeleton included reinforced ribs which, Jenkins speculates, may have supported the creature when it was out of water. It also had wrist bones very similar to those of other ancient creatures believed to have been the earliest land animals, as well as bendable fins that may have supported the beast on land (Powell 2006: 9).
According to the Harvard Gazette, Jenkins' fossil was "a link between fish and land animals..." (ibid. 1, 9). The journal further reported: "When announced in April 2006, the discovery was hailed as the long-sought 'missing link,' filling an evolutionary gap in the history of how fishlike creatures first crawled out of the shallow rivers to take their place on land" (ibid. 9). In fact, the sub-headline to the article referred to a "fish-land animal link" (ibid. 1), while the headline to the second half of the article, continued on a subsequent page, stated: "Researchers fill in key evolutionary gap" (ibid. 9).
Other major news outlets used identical wording to describe Jenkins' discovery, and it has become practically an established fact that Tiktaalik is indeed the incontrovertible missing link between fish and land-dwelling animals. On May 25, 2006, Jenkins even gave a speech at the Harvard Science Center entitled "From Fins to Limbs" (ibid.).
Despite this conventional wisdom, Jenkins himself has expressed reservations about whether Tiktaalik is actually the missing link between fish and ground-walking animals (referred to as tetrapods). As the Gazette reported, "Though Tiktaalik has been widely referred to as a 'missing link,' Jenkins said he thinks the term is a bit of a misnomer and concurs with those who said its discovery just creates two new missing links, one on each side...'This is just one piece of evidence of the great circle of life,' Jenkins said” (ibid.).
The new discovery has created more questions than it has answered. Media outlets should thus use caution in trumpeting Tiktaalik as an irrefutable missing link between fish and the first land-dwelling tetrapods.
Recommended Resources for Further Study
Powell, A. 2006. "Finding a fossilized needle in an Arctic haystack." Harvard Gazette, 1 June.
Stephen Caesar holds his master's degree in anthropology/archaeology from Harvard. He is a staff member at Associates for Biblical Research.