How come Octopuses haven't evolved in the past 100 million years?
And if they are evolving, what are they evolving into?
Science Daily: Cretaceous Octopus With Ink And Suckers -- The World's Least Likely Fossils?
ScienceDaily (Mar. 18, 2009) — New finds of 95 million year old fossils reveal much earlier origins of modern octopuses. These are among the rarest and unlikeliest of fossils. The chances of an octopus corpse surviving long enough to be fossilized are so small that prior to this discovery only a single fossil species was known, and from fewer specimens than octopuses have legs.Indeed: it provides information that none has occured.
Even if you have never encountered an octopus in the flesh, the eight arms, suckers, and sack-like body are almost as familiar a body-plan as the four legs, tail and head of cats and dogs. Unlike our vertebrate cousins, however, octopuses don't have a well-developed skeleton. And while this famously allows them to squeeze into spaces that a more robust animal could not, it does create problems for scientists interested in evolutionary history. ...
Palaeontologists have just identified three new species of fossil octopus discovered in Cretaceous rocks in Lebanon. The five specimens, described in the latest issue of the journal Palaeontology, are 95 million years old but, astonishingly, preserve the octopuses' eight arms with traces of muscles and those characteristic rows of suckers. Even traces of the ink and internal gills are present in some specimens. '
"These are sensational fossils, extraordinarily well preserved," says Dirk Fuchs of the Freie University Berlin, lead author of the report. But what surprised the scientists most was how similar the specimens are to modern octopus: "these things are 95 million years old, yet one of the fossils is almost indistinguishable from living species." This provides important evolutionary information.
Similarly, the tuatara is alleged to be "the fastest evolving animal" yet it's phenotype hasn't changed in 200 million years.