(Roughly) Daily

Artist’s rendering of Ikaria wariootia. It would have lived on the seafloor.

A worm-like creature that burrowed on the seafloor more than 500 million years ago may be key to the evolution of much of the animal kingdom.

The organism, about the size of a grain of rice, is described as the earliest example yet found in the fossil record of a bilaterian.  These are animals that have a front and back, two symmetrical sides, and openings at either end joined by a gut.

The scientists behind it say the development of bilateral symmetry was a critical step in the evolution of animal life.

It gave organisms the ability to move purposefully and a common, yet successful way to organise their bodies.

A multitude of animals, from worms to insects to dinosaurs to humans, are organised around this same basic bilaterian body plan.

Scott Evans, of the University of California at Riverside, and colleagues have called the organism Ikaria wariootia…

How a 555 million year old worm paved our developmental path: “Fossil worm shows us our evolutionary beginnings.”  Read the underlying paper in the journal PNAS.

* Gary Larson

###

As we celebrate symmetry, we might recall that it was on this date in 1858 that Hyman L. Lipman, of Philadelphia was issued the first U.S. patent for a combination lead pencil and eraser (No. 19,783).  The pencil was made in the usual manner, with one-fourth of its length reserved inside one end to carry a piece of prepared india-rubber, glued in at one edge.  Thus, cutting one end prepared the lead for writing, while cutting the other end would expose a small piece of india rubber.  This eraser was then conveniently available whenever needed, and not likely to be mislaid.  Further, the eraser could be sharpened to a finer point to make a more precise erasure of fine lines in a drawing, or cut further down if the end became soiled.

source