Schinderhannes bartelsi

Schinderhannes bartelsi is an anomalocarid known from one specimen from the lower Devonian Hunsrück Slates. Its discovery was astonishing because previously, anomalocaridids were known only from exceptionally well-preserved fossil beds (Lagerstätten) from the Cambrian, 100 million years earlier.[1]

Schinderhannes bartelsi
Temporal range: Early Devonian 408–400 Ma
The holotype of Schinderhannes. Credit: Steinmann Institute/University of Bonn
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: †Dinocaridida
Order: †Radiodonta
Family: †Hurdiidae
Genus: †Schinderhannes
Species:
†S. bartelsi
Binomial name
†Schinderhannes bartelsi
Kühl, Briggs & Rust, 2009

Anomalocaridids, such as Anomalocaris, were organisms determined to be basal arthropods. These creatures looked quite unlike any organism living today—they had segmented exoskeletons, with lateral lobes used for swimming, typically large compound eyes, often set on stalks, and most strikingly, a pair of large, claw-like great appendages that resembled headless shrimp. These appendages are thought to have passed food to the animal's mouth, which resembled a ring of sliced pineapple.[2]

Discovery

The single specimen was discovered in the Eschenbach-Bocksberg Quarry in Bundenbach, and is named after the outlaw Schinderhannes who frequented the area. Its specific epithet bartelsi honours Christoph Bartels, a Hunsrück Slate expert. The specimen is now housed in the Naturhistorisches Museum, Mainz.[1]

Morphology
Life restoration

Schinderhannes is about 10 centimetres (3.9 in) long; like other anomalocaridids, it bears a pair of great appendages (very similar to those of Hurdia),[3] a radial Peytoia 'pineapple-ring' mouth, and large, stalked, compound eyes. It has 12 body segments; large flap-like structures used for swimming protrude from just behind the head, and the 11th segment bears lateral flukelike appendage.[1]

Ecology

The preserved contents of its digestive tract are typical of those of other predators',[4] and this lifestyle is supported by the raptorial nature of the spiny great appendages and the size of the eyes.[1] The organism was clearly a competent swimmer, propelling itself with the 'flippers' attached to its head, and using its wing-like lobes on the 11th segment to steer.[1] These lobes presumably derived from the lateral lobes of Cambrian anomalocaridids, ancestors that used lobes along their sides to swim, and lacked the specializations of Schinderhannes.[1]

Significance

The organism's discovery was most significant because of the huge range extension of the anomalocaridids it caused: the group was only previously known from lagerstätten of the lower-to-middle Cambrian, 100 million years before. This underlined the utility of lagerstätten like the Hunsrück Slate: these exceptionally preserved fossil horizons may be the only available opportunity to observe non-mineralised forms.[5]

The organism has also prompted novel hypotheses about the classification of early arthropods. One classification scheme has Schinderhannes classified basally to the crown arthropods, but closer to that group than Anomalocaris. This would mean that the crown arthropod lineage evolved from a paraphyletic grade of anomalocaridids, and that the group of early arthropods with short 'great appendages' are not a natural grouping.[1] The biramous limb of arthropods may then have arisen through fusion of anomalocaridid lateral lobes and gills.[3]

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References
  1. Gabriele Kühl, Derek E. G. Briggs & Jes Rust (2009). "A great-appendage arthropod with a radial mouth from the Lower Devonian Hunsrück Slate, Germany". Science. 323 (5915): 771–773. Bibcode:2009Sci...323..771K. doi:10.1126/science.1166586. PMID 19197061.
  2. Stephen Jay Gould (1989). Wonderful Life: The Burgess Shale and the Nature of History. W. W. Norton & Company. ISBN 978-0-393-02705-1.
  3. Allison C. Daley, Graham E. Budd, Jean-Bernard Caron, Gregory D. Edgecombe & Desmond Collins (2009). "The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution". Science. 323 (5921): 1597–1600. Bibcode:2009Sci...323.1597D. doi:10.1126/science.1169514. PMID 19299617.CS1 maint: multiple names: authors list (link)
  4. Nicholas J. Butterfield (2002). "Leanchoilia, and the interpretation of three-dimensional structures in Burgess Shale-type fossils". Paleobiology. 28 (1): 155–171. doi:10.1666/0094-8373(2002)028<0155:LGATIO>2.0.CO;2. JSTOR 3595514.
  5. Nicholas J. Butterfield (1995). "Secular distribution of Burgess-Shale-type preservation". Lethaia. 28 (1): 1–13. doi:10.1111/j.1502-3931.1995.tb01587.x.

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