Archive of Projects on 'Orsten' Fossils Finished by the Ulm Team

2008

Oelandocaris oelandica Müller, 1983 – see references

Our investigations have led to the discovery of various new features. One is the huge antennula comprising of three long spike-bearing extensions. Another is that there is only a single proximal endite, one of the crustacean features sensu Walossek & Müller (1990), present on the third head limb (mandibula). The proximal endite is embedded within the arthrodial membrane at the inner proximal edge of the basipod. Again, fine pores on the thoracic tergites and the large flap-shaped exopods of the serial post-„mandibular“ limbs (plesiomorphy) may have been the holes for sensilla.

This supports a mainly swimming life of this form considered as a derivative of the stem lineage of the Crustacea toward the Labrophora.

With the help of two young volunteers – pupils from the Humboldt Gymnasium in Ulm –, we had buildt a plasticine model (500 times magnification), which we used for our reconstruction of the morphology and for the improvement of our understanding of functional-morphological aspects (food intake etc.).

Subsequently Martin Stein, our member from Uppsala, Sweden, started to build models in Blender – actually he started this –, which even became animated recently. This allows a first glimpse onto the heterochronic beating and swimming of such animals in a surprisingly plausible way.

2007

The first eucrustacean from the Lower Cambrian, Yicaris dianensis – see references

The first paper on the Chinese Lower Cambrian Yicaris dianensis Zhang, Siveter, Waloszek & Maas, 2007 is now published. Currently we are planning a more detailed publication on the epipodite-bearing new form that has a significant bearing on assumptions on the early evolution of the crustacean crown group.

Yicaris is, according to our analysis, a member of the crowngroup of Crustacea, the eucrustaceans, and, even, more, fits nicely into the Entomostraca, so strengthening the monophyly of this taxon. This can be drawn from several features, which are shared only with cephalcoarids, maxillopods and branchiopods, members of this clade. See more on the page "Evolutionary implications".

Furthermore, Yicaris has two remarkable features to be added to the discussion of eucrustacean/ entomostracan features: epipodites (see also this paper on the evolution of epüipodites in crustaceans) and six-segmented endopods on the trunk limbs.

Lastly, the endopods of the anterior limbs have more endites than known from any of the extant entomostracans and any of the hitherto described 'Orsten' forms representing members of this clade: Dala, Bredocaris, Skaracarida, Walossekia and Rehbachiella.

Cambrian Series 3 lobopodian – see references

This was an investigation in co-operation with Reinhardt M. Kristensen, Copenhagen, Denmark and Georg Mayer, currently Australia: The new form is indeed the smallest, the youngest and the best preserved lobopodian ever found.

The most important aspect of the animal from the Swedish Orsten is: It has a single gonopore, see on right, just as in Recent onychophorans, below the image. This is the definite proof that arthropods, having paired gonads with gonoducts, but started out having a single gonopore and not paired ones as, e.g. in eucrustaceans (known only from living forms).

Another new aspect is its insertion of the appendages ventro-laterally at a kind of bridg, which preformed the orientation to a strict lateral one. The most likely pretty long legs were as tubular as the body and liekwise annulated.
Anteroventrally and posteroventrally they bore spine-like outgrowths of two diferent types, a multicelluar outgrowth and a telescoping spine nesting in a socket. We could identify this so well because the specimens are hollow and we could look into the leg! IMAGES SOON! These spines must have been used to anchor and push the legs so that they could operate in a crawling llike lizzards, but with more legs involved.

A longer version including also a detailed account on the cuticular features and the legs is currently under way.

2006

Short overview on the 'Orsten', taphonomic aspects and occurrences on a world-wide scale
(Maas et al. 2006)

This is our first joint venture (Maas et al. 2005, short communication presented on a conference in Nanjing, China) bringing together data from several of us about Orsten-type preservation and the current record of such preservation, including latest information on material from China. The second, larger paper has been published before Christmas 2006.

Pentastomids (see references)

The third paper on a Cambrian pentastomid – a collaboration between the C.O.R.E. members John Repetski, Reston, U.S.A., Andreas M. and Dieter W. – dealt mainly with a new Cambrian species, named Aengapentastomum andresi, from Västergötland (on right side). It also expanded to review our current knowledge about the evolution of pentastomids in their co-evolutionary path with craniotes, , pdf on request.

2005

New data on Oelandocaris oelandica Müller, 1983 (see Stein et al. 2005)

First data have been presented in a short paper, pdf on request, detailed work is under way (submitted), see under Running Projects.

2003

Phosphatocopina (see Maas et al. 2003, also Maas & Waloszek 2005)

A big monograph published 2003 and a short version published in 2005, pdf on request. Phosphatocopina are the sister taxon of Eucrustacea sharing a large number of significant features, such as the labrum, the coxa on antenna and mandible, the sternum, the paragnath humps on the mandibular part of the sternum and fine setulae on sternum, labral flanks and setae of the limbs. These features are all missing in the stem taxa. The taxon embracing Phosphatocopina and Eucrustacea has been named LABROPHORA, formally by Siveter et al. (2003, pdf on request).

Phosphatocopina hatch with a head larva, a plesiomorphic feature, but this larva has "already" the characteristic bivalve shield embracing the whole body (autapomorphy of this taxon). Furthermore, the phosphatocopine antennulae are tiny and the trunk region is highly reduced. Plesiomorphic are the serial arrangement of the postmandibular limbs (no limb pair specialized to maxillae), a large proximal endite on all post-mandibular limbs, and no movable endites along the basipod.

This morphology stands opposite to that of the Eucrustacea, which possess, in their ground pattern, a nauplius – a larva with all features developed in the stem species of Labrophora (labrum, coxa on antenna and mandible, sternum, paragnath humps on the mandibular part of the sternum and fine setulae on sternum, labral flanks and setae of the limbs), and a specialized fourth head limb, the so-called maxillula.

Klausmuelleria salopensis Siveter, Waloszek & Williams, 2003 (Siveter et al. 2003)

The single specimen discovered in Comley, UK, turned out to represent the hitherto oldest 3d-preserved arthropod, the oldest phosphatocopine and oldest arthropod larva. A short pre-version was published in Science by Siveter et al. (2001, pdf on request).

2002

Cambropycnogon klausmuelleri Waloszek & Dunlop, 2002 (in Waloszek & Dunlop 2002)

In this paper Jason and Dieter described in detail the hitherto only 3d chelicerate of the 'Orsten' (pdf on request), prepresenting a pycnogonid and sister taxon to all other fossil and Recent pycnogonids (Pantopoda is the crown group). Retaining a classical view, they remained interpreting the cheliphore as the second appendage and a pair of tiny outgrowths flanking the mouth as possibly the antennulae. This view could be corrected by Vilpoux & Waloszek (2003, pdf on request) on the basis of own studies of the larval development of the Recent pantopod Pycnogonum litorale (Ström, 1763) and evidence from different disciplines.