February 28, 2011 | David F. Coppedge

Amazing Animals

Three recent articles about amazing animals and fossils deserve entries of their own, but due to lack of time, will be corralled here lest, like strays, they wander off.

  1. Turtle navigation:  Wired Science has a beautiful photo of a marine turtle in an article about how they achieve a difficult navigational skill: determining longitude from the earth’s magnetic field.  By varying magnetic fields in research ponds with hatchlings, researchers at the University of North Carolina determined that, “Against reasonable expectation, the turtles clearly sensed differences in geomagnetic angle.”  See also New Scientist and Science Daily.
        Human efforts to determine longitude required accurate clocks.  The researchers didn’t explain precisely how the turtles do it, other than to rule out biological clocks.  They were clearly astonished by animal navigation in general: “That turtles and other migratory animals could detect such a small change was considered unrealistic, but experiments on animals released in out-of-the-way locations repeatedly described them finding home with unerring accuracy and efficiency, explicable only as a product of both longitudinal and latitudinal awareness.
  2. Cat bite:  The BBC News reported on new findings about how sabretooth cats like Smilodon were able to close their mouths with those long, dagger-like teeth.  Studies of the bones and neck muscle insertion points by a team at Aalborg University in Denmark “revealed how the cats’ jaw muscles were aligned to pull its jaws closed, very directly and efficiently.”  The article ascribed all this efficiency to evolution.
  3. Charismatic behemoth:  A new sauropod species described on Science Daily had legs like bars of iron, by Job.  “Brontomerus mcintoshi, or ‘thunder-thighs’ after its enormously powerful thigh muscles,” found in Utah, may have kicked its attackers to kingdom come.  “‘Brontomerus mcintoshi is a charismatic dinosaur and an exciting discovery for us,’ said first author Mike Taylor, a researcher in the Department of Earth Sciences at University College London.”
        Less emphasized in the article was the worry that this discovery undermines previously-held beliefs about sauropods – i.e., that they were disappearing by the Cretaceous.  “It now seems that sauropods may have been every bit as diverse as they were during the Jurassic, but much less abundant and so much less likely to be found.

Evolution was largely ignored in these stories.  None of the popular articles on turtle navigation mentioned it, but the source paper in Current Biology1 only mentioned it in passing – “These results are consistent with the interpretation that birds, like turtles, have evolved a way to assess longitude that is independent of time-keeping.”
    Similarly, most of the dinosaur articles did not mention evolution.  A researcher quoted in Live Science speculated, “We think the most likely reason this evolved was over competition for mates,” but once it evolved, “it would be bizarre if it wasn’t also used in predator defense.”  This makes it clear that the bones did not give a definitive answer to how thunder-thighs grew a thighs size to kick enemies asunder.
    The BBC article on sabretooth cats mentioned evolution the most.  There, however, evolution was merely assumed: e.g., “the cats’ jaw muscles evolved into a specialised pattern, which allowed them to open their mouths so wide.”  The article talked about “how Smilodon evolved” and how the researchers drew an “evolutionary map” to show how “sabretooths evolved longer canine teeth” under “evolutionary pressure to kill prey with a deep and efficient stab to the throat.”2  Even if there was variation among cats and their fangs, the fangs already existed in cats, and the cats and all their musculature already existed in the cat family.  Even young-earth creationists would not disagree that variation in existing genetic information could lead to adaptations in particular environments.

1.  Putnam et al, “Longitude Perception and Bicoordinate Magnetic Maps in Sea Turtles,” Current Biology, 24 February 2011, doi:10.1016/j.cub.2011.01.057.
2.  Note: “evolutionary pressure” is a misnomer.  Natural selection may constrain variation by preventing survival of mutants, but provides no pressure, impetus, guidance, force or direction (see 01/24/2008).

Evolution was tacked-on to some of these stories like hot sauce on ice cream.  It had nothing to do with the facts of the story and created a bad aftertaste to otherwise interesting stories about amazing creatures.  Scrape off the hot sauce best you can.  (Don’t stir it.)

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