Tá lobopodian armúrtha aisteach ón Cambrian

Na farraigí Cambrian luath (542-488 milliún bliain ó shin) had a plethora of strange and bizarre creatures almost unimaginable to even the best sci-fi dreamer. Mar b'fhéidir, ar cheann de na réamhtheachtaithe ar an Arthropoda (freisin Onychophora agus Tardigrada), ionadaíocht a dhéanamh ar lineages lobopodian grúpa aisteach de “worms le cosa” that once roamed the ancient sea beds. Exactly how close they are to the true arthropods is up for debate (tree below), but this newly discovered genus and species, Diania cactiformis (walking cactus), represents the most well sclerotized and arthropod-like of any known to date.

This whopping two and a half inch monster helps us understand the transition from a soft bodied worm like creature into a hard-shelled arthropod; it also gives a better impression of how diverse these lobopodian appendages may have been. It’s a fascinating question because the advantage of jointed, sclerotized, limbs was one that exploded and diversified amongst the creatures we know today. Exactly how this happened is not any closer to being resolved, but it appears as if the legs of this animal were sclerotized before the body (arthropodization vs. arthrodization). One small fossil discovered and yet another small insight into evolutionary history.

Tagairtí

Liu, J., Steiner, M., Dunlop, J., Keupp, H., Shu, D., Ou, Q., Han, J., Zhang, Z., & Zhang, X. (2011). An armoured Cambrian lobopodian from China with arthropod-like appendages Nature, 470 (7335), 526-530 DOI: 10.1038/nature09704

Further reading: A colleagues blog on the lobopodian in Hungarian.