Ezkerraldean
June 18, 2006, 09:49 AM
wow. amazing examples of wierd fossils from the precambrian/cambrian- which resemble mixtures of different phylums and classes of animals. These are (based on morphology and dating) often considered to be "transitional forms"
Halkieria (sirius passet, cambrian) An "armoured worm", thought to be a link between brachiopods and annelids
Marrella (burgess shale, cambrian) strongly resembles the earliest trilobites in shape, but smaller and soft-bodied, presumably swimming
Tegopelte (cambrian) and Sidneyia (cambrian) - resemble both trilobites and anomalocarids
Burgessia (cambrian) - resembles both trilobites and supposed ediacaran ancestors of trilobites
(absolutely stunning wealth of cambrian arthropods, all with variants on the trilobite body plan - http://www.trilobites.info/triloclass.htm )
Haikouella (chengjiang, cambrian) - resembles both Pikaia and modern lancelets
Spriggina (ediacaran) - resembles trilobites and numerous other Burgess arthropods
Parvancorina (ediacaran) - resembles early small trilobites and Marrella
Kimberella (siberia, ediacaran) - a possible ancestral mollusc? Also resembles the enigmatic ediacaran Dickinsonia, with a more prominent central groove
the cambrian/precambrian boundary biota is incredible, a field i really want to study in myself eventually. its interesting to see how the continuing discovery of soft-bodied animals from the ediacaran, and the earliest cambrian, are confirming molecular clock measurements and previous theories.
There is even now an ediacaran vertebrate!!! ( http://pharyngula.org/comments/A105_0_1_0_C/ ) although personally I am not convinced. looks to me just like spriggina.
Halkieria (sirius passet, cambrian) An "armoured worm", thought to be a link between brachiopods and annelids
Marrella (burgess shale, cambrian) strongly resembles the earliest trilobites in shape, but smaller and soft-bodied, presumably swimming
Tegopelte (cambrian) and Sidneyia (cambrian) - resemble both trilobites and anomalocarids
Burgessia (cambrian) - resembles both trilobites and supposed ediacaran ancestors of trilobites
(absolutely stunning wealth of cambrian arthropods, all with variants on the trilobite body plan - http://www.trilobites.info/triloclass.htm )
Haikouella (chengjiang, cambrian) - resembles both Pikaia and modern lancelets
Spriggina (ediacaran) - resembles trilobites and numerous other Burgess arthropods
Parvancorina (ediacaran) - resembles early small trilobites and Marrella
Kimberella (siberia, ediacaran) - a possible ancestral mollusc? Also resembles the enigmatic ediacaran Dickinsonia, with a more prominent central groove
the cambrian/precambrian boundary biota is incredible, a field i really want to study in myself eventually. its interesting to see how the continuing discovery of soft-bodied animals from the ediacaran, and the earliest cambrian, are confirming molecular clock measurements and previous theories.
There is even now an ediacaran vertebrate!!! ( http://pharyngula.org/comments/A105_0_1_0_C/ ) although personally I am not convinced. looks to me just like spriggina.