'' A slab and counter slab, more often called a part and counterpart in paleoentomology and paleobotany, are the matching halves of a compression fossil, a fossil-bearing
matrix formed in
sedimentary deposits. When excavated the matrix may be split along the natural grain or cleavage of the rock. A fossil embedded in the sediment may then also split down the middle, with fossil remains sticking to both surfaces, or the counter slab may simply show a negative impression or mould of the fossil. Comparing slab and counter slab has led to the exposure of a number of fossil forgeries. Differences between the impressions on slab and counterslab led astronomer
Fred Hoyle and applied physicist
Lee Spetner in 1985 to declare that some
Archaeopteryx fossils had been
forged, a claim dismissed by most palaeontologists. In its November 1999 edition,
National Geographic magazine announced the discovery of
Archaeoraptor, a link between dinosaurs and birds, from a 125 million-year-old fossil that had come from
Liaoning Province of China. Chinese palaeontologist
Xu Xing came into possession of the counter slab through a fossil hunter. On comparing his fossil with images of
Archaeoraptor it became evident that it was a composite fake. His note to
National Geographic led to consternation and embarrassment. Lewis Simons investigated the matter on behalf of
National Geographic. In October 2000, he reported what he termed: It was eventually determined that
Archaeoraptor had been constructed from parts of an
Early Cretaceous bird
Yanornis martini and a small dinosaur
Microraptor zhaoianus. In order to increase their profit, fossil hunters and dealers occasionally sell slab and counter slab separately. A reptile fossil also found in Liaoning was described and named
Sinohydrosaurus in 1999 by the
Beijing Natural History Museum. In the same year the
Institute of Vertebrate Paleontology and Paleoanthropology in Beijing described and named
Hyphalosaurus lingyuanensis, unaware they were working with the counter slab of the same specimen.
Hyphalosaurus is now the accepted name. ==References==