January 18, 2006 | David F. Coppedge

How to Squeeze Fossils Into Evolutionary Trees

Fossils do not come with dates or labels on them.  Sometimes it is quite a puzzle to figure out where they fit in Darwinian ancestral trees.  One such example was published in Nature on January 12 by Chinese scientists who found an oddball in the famous Liaoning fossil beds.1  They called it a “Cretaceous symmetrodont therian with some monotreme-like postcranial features” (monotremes include the famous duck-billed platypus), and named it Akidolestes cifellii.
    There are some technical terms in the paper that require translation: apomorphy, homoplasy, and plesiomorphy among them (thank goodness for Dictionary.com).  One phrase jumped out of the otherwise jargon-laden paper: “rampant homoplasy.”  A quick check shows this word homoplasy to be a synonym for “convergent evolution,” the idea that unrelated animals “converged” on similar body parts.

Within eutriconodontans, lumbar ribs are present in gobiconodontids but not in the related Jeholodens.  Within spalacotheroids, these are present in Akidolestes but absent in zhangheotheriids.  Outside the crown mammals, lumbar ribs are absent in morganucodontans but variably present in many advanced cynodonts.  It is possible that this rampant homoplasy of the lumbarosacral vertebral ribs is patterned by developmental genes that are deeply conserved in widely separated mammalian taxa that lacked a recent common history.  However, homoplastic development of the lumbar ribs is not mutually exclusive of the interpretation that these ribs and related features also have convergent function to extant monotremes.   (Emphasis added in all quotes.)

Those who wish can insert most of the terms in the above quote into Dictionary.com or google the various animal group names.  The upshot is that this fossil, and many others in other “widely separated” mammal groups, show “rampant homoplasy” (convergence) of several “post-cranial features” (i.e., parts behind the skull, or, in other words, the rest of the body).  The authors are suggesting here two possible explanations for these similarities: (1) developmental genes for these structures are “deeply conserved” (i.e., they began way, way back in time before these groups split apart), or, (2) somehow the environment forced their body plans to become similar (“convergent function”).
    The following sentence from the abstract jargonizes these two choices: “These peculiar features may have developed as functional convergence to locomotory features of monotremes, or the presence of lumbar ribs in this newly discovered mammal and their absence in its close relatives might be due to evolutionary developmental homoplasy.”  The authors confessed some astonishment at their find: “this new mammal revealed some surprisingly convergent features to monotremes in the lumbar vertebrae, pelvis and hindlimb.” 
    A reading of the paper reveals that they had some confusion deciding where to place this mammal.  It seems to have a mosaic of features from distantly related groups.  Isn’t that what happened with Platypus itself?  When first discovered, some taxonomists were convinced this strange animal with a duck’s bill and webbed feet, a snake’s venom and a mammal’s hair was an Aussie hoax.  It wasn’t.

1Gang Li and Zhe-Xi Luo, “A Cretaceous symmetrodont therian with some monotreme-like postcranial features,” Nature 439, 195-200 (12 January 2006) | doi:10.1038/nature04168.

Words like “homoplasy” and “convergent evolution” are surreptitious gimmicks evolutionists use to hide their naked assumptions.  When data are not cooperative, when fossils exhibit “surprisingly convergent features,” when evolutionary paleontologists don’t have the foggiest idea where to hang their ornaments on the tree, they use such hand-waving terms to pretend their speculations are scientifically based.  Here you see the “stretch and squish” theory of “evolutionary agility” (12/14/2004) in action, with working magicians manipulating words to keep Darwinism safe from the observations.  Don’t be fooled (see Smokescreens in the Baloney Detector).

(Visited 14 times, 1 visits today)
Categories: Fossils

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.