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Our Cambrian Creche

As the old saying goes, in a country of blind men the one-eyed man is King.

But what about five eyes and a single grasping claw? This is Opabinia, a representative of a novel phylum that spontaneously arose during the Cambrian age, 500 million years ago:

Unfortunately, for some reason this guy didn’t "make the cut", and failed to survive the "Cambrian extinction", an evolutionary screening event that sent many of the newly developed Cambrian design experiments to their graves. Considering that the Cambrian age was the time when eyes were invented, why wouldn’t "more" be better?

Along with him expired hallucigenia, a truly weird prototype with spikes for feet and a number of hollow breathing (feeding?) tubes along its back:

It’s entirely possible that paleontologists have been depicting him upside-down. Maybe the tubes were actually his feet, and the spines were pointed up as protection, as in Wiwaxia, another Cambrian creation:

Fortunately for us, this fellow did survive: Haikouella lanceolata, put forward as the earliest Chordate -- from which evolved vertebrates including fish and fowl, dinosaurs and donkeys, monkeys and men. Quite a humble beginning indeed -- and possibly instructive in some sense for the egocentric assholes around us that continually boast about their special position in the Universe. But for the grace of God -- or of Fate, if you prefer -- this particular biological experiment might have expired too…

Figure 2. Anatomical interpretation of Haikouella lanceolata (gen. et sp. nov.). Abbreviations: Abv (anterior branchial vessel); An (anus); Ap (anterior projection); At (atrio); Atp (atriopore); Ba (branchial arches); Baf (banchial-arch-filamentals); Br (brain); Buc (buccall cavity): Co (copulatory organ); Cp (caudal project); Da (dorsal aorta); Df (dorsal fin); Ds (denticular structure); Eg (endostyle glands); Es (endostyle); Esp (esophagus); Hd (head); Ht (heart); It (intestine); Lb (lobated structures); Le (lateral eye); Mg (midgut); Mm (myomeres); Mo (mouth opening); Ms (myosepta); Mw (median wall); Nc (neural cord); Nt (notochord); Ph (pharyngeal cavity); T (tentaclelike structure); Va (ventral aorta); Vf (ventral fin).

Of course, some (Gould, et. al.) point to an alternate possible candidate for the earliest chordate, known as Pikaia. This chap is found slightly later, in middle-Cambrian era fossils:

Personally, I have a hard time figuring out which side the "head" is at. So do paleontologists. There is no evidence of sensory organs on this guy, nor brain, nor much else. All that is evident is the presence of an apparent notochord, an early spinal column -- the key characteristic of a vertebrate. I much prefer Haikouella as my old man…

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