Species Accounts

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last revised 06 June 2008 by S.M. Gon III

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Species Accounts IV - Kerygmachela kierkegaardi & Pambdelurion whittingtoni
This page features images of the fossils and reconstructions of two unusual species from Sirius Passet, Greenland: Kerygmachela kierkegaardi and Pambdelurion whittingtoni. They are not typically included among the anomalocaridids, because they bear lobopodal limbs, rather than the arthropodan form of the anterior limbs of typical anomalocarids. However, their similarities to anomalocarids in general form bear depiction and discussion.

*Kerygmachela kierkegaardi* One of the type specimens of the Sirius Passet lobopod Kerygmachela kierkegaardi is not complete, and the imperfect preservation shows a pair of broad, annulated anterior appendages bearing numerous spines, lateral lobes (ill-defined) and a series of dorsal axial tubercles and striations remarkably like those of fossil and extant lobopods. The strongly-developed anterior limbs, 11 lateral lobes, and a pair of posterior cerci (not preserved in this specimen, but present in others) fit the anomalocaridid bauplan.	*Kerygmachela kierkegaardi* *...* The camera lucida drawing of the specimen at left shows the suggestive anomalocaridid bauplan of elongate body, numerous lateral lobes, and a pair of well-developed, anterior limbs bearing spines. There are even gill-like striations on the lateral lobes, as seen in the Burgess anomalocarid Laggania. The pericardial sinus and onychophoran dorsal striations and tubercles are not typical of other anomalocarids, however, making this taxon a problematic species.
My reconstruction of the dorsal view of Kerygmachela kierkegaardi depicts the general body plan of the specimen depicted above, but also shows features clearly present in other specimens, such as the long anterior spines borne by the anterior limbs, the long, annulated pair of cerci, and the repeating sets of tubercles and striations on the body. There are a pair of anterior organs that may be eyes.	The ventral view of Kerygmachela kierkegaardi shows its lobopodal legs, as well as the conical mouthparts that open anteriorly (rather than in the ventral 'Peytoia'-like array of typical anomalocarids). As a leg-bearing animal, Kerygmachela seems to show affinities to both anomalocarids and Cambrian lobopods.

*Pambdelurion whittingtoni* Like Kerygmachela, specimens of Pambdelurion are not easily interpreted. This specimen shows the ovoid body, well-developed lateral lobes, and paired indentation where lobopodal legs occur. Axial structures are interpreted as gut and paired diverticulae.	*Pambdelurion whittingtoni* . . The camera lucida drawing of the specimen at left show some of the details that are apparent only when working directly with the specimen. Once again, there are 11 lateral lobes present, as in the majority of anomalocarids, but otherwise the bauplan is very much like the Burgess lobopod Aysheaia, with large lobopod limbs running the length of the body.
This camera lucida drawing of another specimen of Pambdelurion that shows the flexible and massive anterior limbs also reveals the Peytoia-like mouth, and array of lateral lobes. Unlike other anomalocarids, the terminal spines borne on the anterior limbs seem flexible.	. My reconstruction of Pambdelurion shows the massive pair of anterior limbs with their brushlike spines, the 11 lateral lobes, and the gut with paired diverticulae. The Peytoia-like mouth and lobopodal limbs create a strange conflict between mouth and body features that are clearly anomalocarid, but limb features that seem of paraphyletic origin. There is no sign of posterior cerci or fantail.