Pikaia gracilens is an extinct, primitive chordate marine animal known from the Middle Cambrian Burgess Shale of British Columbia.

Pikaia – from the pika, a small alpine mammal and cousin of the rabbits. Pikas live in the Rocky Mountains, including near the Burgess Shale. gracilens – from the Latin gracilens, “thin, simple,” in reference to the shape of the body.

The first Cambrian chordate known is Pikaia gracilens, a lancelet-like animal from the Burgess Shale in British Columbia, Canada. The discoverer, Charles Doolittle Walcott, described it as a kind of worm in 1911, but it was later identified as a chordate. [1]

2012年3月6日 · The research team’s analysis proves the extinct Pikaia gracilens is the most primitive member of the chordate family, the group of animals that today includes fish, amphibians, birds, reptiles and mammals.

…oldest known fossil chordate is Pikaia gracilens, a primitive cephalochordate dated to approximately 505 million years ago. There is disagreement over whether older animals—such as Yunnanozoon lividum and Haikouella (both of which date to 530 million years ago and possess several chordate features)—should be considered chordates.

2024年7月8日 · Here we reinterpret the morphology of Pikaia, providing evidence for a gut canal and, crucially, a dorsal nerve cord—a robust chordate synapomorphy. The identification of these structures underpins a new anatomical model of Pikaia that shows that this fossil was previously interpreted upside down.

2024年6月24日 · Annotated photos show the newly revised organization of Pikaia gracilens. Abbreviations in box C indicate key features in the fossil seen in box B: tentacles on Pikaia's head (Tc);...

2012年3月6日 · The Middle Cambrian Pikaia gracilens, from 505 million years ago, was a fish-like worm, which has the possible dubious distinction of being one of humanity's earliest genetic ancestors. These fish-like worms had the beginning of spines, including a notochord and a nerve chord, which wasn't obvious t

The Middle Cambrian Pikaia gracilens (Walcott) has an iconic position as a Cambrian chordate, but until now no detailed description has been available. Here on the basis of the 114 available specimens we review its anatomy, confirm its place in the chordates and explore with varying degrees of confi …

For the past 35 years, the Cambrian fossil Pikaia gracilens was widely interpreted as a typical basal chordate based on short descriptions by Conway Morris. Recently, Conway Morris and Caron (CMC) (2012, Biol Rev 87:480-512) described Pikaia extensively, as a basis for new ideas about deuterostome e …