July 30, 2006 | David F. Coppedge

Opal Plesiosaurs, Flashy Pterosaurs and Hot Titanosaurs Inspire Stories

Paleontologists continue to dig up bones of fascinating species of long-lost animals.  When it comes to extinct species, the line between observation and interpretation becomes fuzzy, since there is no way to be absolutely sure how they behaved and what they were doing when they died.  This does not prevent scientists from freely speculating on what the bones tell us.

  • Precious stone bones:  Two new species of plesiosaur were discovered in Australia this month, according to the BBC News.  The bones of the beasts were replaced by opal minerals that seeped in and replaced the original fossil-bearing rock.  Interpretation: one species had crests on its head, “perhaps for display or mating purposes.”  Other inferences were stated, with copious use of possibility words: suggests, believe, and might have; other times, interpretations are stated as matters of fact:

    They are thought to be of juvenile animals, suggesting the lake was a breeding and nursery ground.
        Scientists believe sea-dwelling adults returned to the shallow inland waters to breed and raise their young.
        At the time, Australia was much colder, and the inland ocean would have frozen over in places during the winter.
        Scientists believe the creatures might have evolved mechanisms to cope with the harsh climate, such as a faster metabolic rate.  They were carnivorous, feeding on fish and squid.

  • Crest aphrodisiacs:  Another BBC News story talks about the exotic head crests on a rare species of pterosaur in Brazil.  Scientists found a younger juvenile with a less-developed crest.  Interpretation: the crest arose as a sexual display during puberty.  At least Dr. Darren Nash left the door open for doubt: “We don’t know this but we imagine they would have bobbed it around and used it to attract other pterosaurs.”  The title of the article said, however, that a flying reptile mystery was “solved.”
  • Hot beef:  Earlier in the month, Live Science and other news sources reported on a study that suggested body temperature was a function of dinosaur size.  The interpretation was based on models that correlated dinosaur growth rates with maximum size as adults.  From here, it was speculated that the largest beast was 118 degrees Fahrenheit, and that temperature was the main factor setting a size limit.  The article also speculates, “Dinosaurs likely got warmer as they became adults.”

Speaking of big beasts, National Geographic News reported a new record: Puertasaurus, a sauropod of the titanosaur group, found in Argentina.  One back vertebral bone is nearly as big as a small car.  An artist’s rendition shows the monster with beefy calves and monster quads, and a chest 16 feet across.  They estimate it grew to be 130 feet long, weighing 110 tons.  (Only neck, back and tail bones were found, so the rest is extrapolated from other species.)

Bones are interesting, dinosaurs are fun, and gathering data is good Baconian exercise.  Most people are not content with dry accumulations of facts, however, and want a story to put them in context.  Scientists are usually happy to oblige this desire.  It’s nice when they go to the trouble to state when the facts end and the speculation begins.  All too often they leave that task to the reader – and the artist.

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Categories: Dinosaurs, Fossils

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