Taxonomy

Phylum: Arthropoda

Class: Megacheira Order：

Order：uncertain

Family: Kootenichelidae

Genus：Kootenichela

Specie: Kootenichela deppi

Description:

The cephalon is 4 mm long (,10% preserved body length),measured from the anterior-most margin to the postero-dorsal margin.This is best preserved in the part and consists of two distinct regions: a narrow anterior and an expanded posterior.The anterior region bears two large pedunculate eyes 0.9 mm in diameter; a small rounded stain within the cephalon is the right eye and appears to preserve individual lenses.Individual lenses can also be distinguished on the left eye and number 50/mm2.The posterior margin of the cephalon curves antero-ventrally and encompasses at least the ‘‘great-appendages’’ and possibly an antenna-like appendage on the ocular segment. There are no other cephalic limbs although the posterior of the cephalon appears to overlap the first trunk tergites, which led to the previous misinterpretation that it possessed four-limb bearing segments.Numerous striations in the posterior part of the cephalon may indicate that it was convex in life and was crushed post-mortem. The putative antenna is preserved as a narrow, almost filamentous staining with little structural detail. This structure is interpreted as a true

biological structure rather than abiogenic staining, which is not found elsewhere in material from this horizon. Gaps in the staining may represent antennal segments. The ‘‘great-appendages’’ are composed of a bipartite proximal peduncle and three distal

spine-bearing podomeres.Although poorly preserved in the holotype, the spines have similar proportions and degree of recurvature to those in a well-preserved isolated pair of cooccurring ‘‘great-appendages’’ that are herein considered conspecific. The most proximal spinebearing podomere has the longest spine, 11.1 mm in length (70% total appendage length), less robust than the others and slightly recurved.An anterior gut trace is preserved;this documents a ventrally directed mouth and extends into the anterior cephalic region , where the dark staining may result from gut-rupture.Midgut glands extend from the gut into the posterior cephalon and trunk and consist of tri-or tetra-radiate finger-like projections. They extend posteriorly to (at least) segment 6, and a strand of unbranched gut is preserved between segments 8 and 15.The preserved part of the trunk in the holotype is 43.5 mm long and consists of 29 segments,tapering posteriorly. Each segment bears a single pair of limbs.

Age & Localities

Age：Cambrian (Series 3, Stage 5), Burgess Shale Formation

Principal localities: Burgess biota (in Yoho National Park,British Columbia,Canada)