• Question: how long do you date back to?

    Asked by guineapiggirl124 to Barn Owl, Brown garden snail, Common Crane, Emperor Dragonfly, Hazel Dormouse, Catshark, Scotch Thistle, St Kilda Wren on 8 Dec 2017. This question was also asked by babble, sbyrnes771.
    • Photo: Lesser-Spotted Catshark

      Lesser-Spotted Catshark answered on 8 Dec 2017:

      Cartilaginous fishes including sharks diverged from bony fishes (including the lineage leading to humans) about 450 million years ago. Catsharks are a bit younger, at about 250 million years. Getting absolute dates for the origins of different species is very difficult without a combination of fossil evidence and whole genome data. If we have the genome sequenced we should be able to help refine these date estimates!

    • Photo: Common Crane

      Common Crane answered on 8 Dec 2017:

      Some believe that Common Crane’s predecessors (infraorder Grui) evolved during Cenozoic period 60 million years ago. Those developed into two lines, one of which (Geranoidea) died out. The other one (Gruoidea) gave us the contemporary cranes.

    • Photo: Emperor Dragonfly

      Emperor Dragonfly answered on 8 Dec 2017:

      So, dragonfly fossils are known that are 300-400 Million years old, so the Odonata (the group of insects that dragonflies are part of) is pretty old…

      Another way of looking at it is to think when dragonflies and people last shared a common ancestor – so when did an organism exist that split into two species that eventually ended up with humans and dragonflies.

      You can do this a a website called Timetree (http://www.timetree.org/) – if you put in “Anax imperator” (the Emperor Dragon fly ) and “Homo sapiens” (that’s humans – you have to use proper Latin name) then you’ll find we shared a common ancestor 796.6 million years ago, back in the Cryogenian era! (a long time ago).

      Have a go it is very cool (and there is an iPad / iPhone app too!)

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