# Compression fossil > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Compression_fossil > Markdown URL: https://mediated.wiki/source/Compression_fossil.md > Source: https://en.wikipedia.org/wiki/Compression_fossil > Source revision: 1344426522 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|none}} [[Image:FossilFernLeavesPennsylvanianOhio.jpg|upright=1.35|thumb|Fossil [seed fern](/source/seed_fern) leaves from the Late [Carboniferous](/source/Carboniferous) of northeastern [Ohio](/source/Ohio).]] A '''compression fossil''' is a [fossil](/source/fossil) preserved in [sedimentary rock](/source/sedimentary_rock) that has undergone [physical compression](/source/compression_(physical)). While it is uncommon to find [animal](/source/animal)s preserved as good compression fossils, it is very common to find [plant](/source/plant)s preserved this way. The reason for this is that physical compression of the rock often leads to distortion of the fossil. The best fossils of [leaves](/source/leaf) are found preserved in fine layers of [sediment](/source/sediment) that have been compressed in a direction [perpendicular](/source/perpendicular) to the plane of the deposited sediment. Since leaves are basically flat, the resulting distortion is minimal. [Plant stem](/source/Plant_stem)s and other three-dimensional plant structures do not preserve as well under compression. Typically, only the basic outline and surface features are preserved in compression fossils; internal [anatomy](/source/anatomy) is not preserved. These fossils may be studied while still partially entombed in the sedimentary rock matrix where they are preserved, or once lifted out of the matrix by a peel or transfer technique. Compression fossils are formed most commonly in [environment](/source/ecosystem)s where fine sediment is deposited, such as in [river delta](/source/river_delta)s, [lagoon](/source/lagoon)s, along [river](/source/river)s, and in [pond](/source/pond)s. The best rocks in which to find these fossils preserved are [clay](/source/clay) and [shale](/source/shale), although [volcanic ash](/source/volcanic_ash) may sometimes preserve plant fossils as well. ==Slabs== [[File:Pterodactylus antiquus p and cp.jpg|upright=1.35|thumb|Counter slab (left) and slab (right) of ''[Pterodactylus](/source/Pterodactylus)'']] {{multiple image | align = right | direction = horizontal | image1 = Longipteryx chaoyangensis (BMNHC Ph930A) NMNS.jpg | width1 = 150 | image2 = Longipteryx chaoyangensis (BMNHC Ph930B) NMNS.jpg | width2 = 150 | footer = Slab (left) and counter slab (right) of ''[Longipteryx](/source/Longipteryx)'' }} A slab and counter slab, more often called a part and counterpart in paleoentomology{{cite journal |last1=Jepson |first1=J.E. |last2=Ansorge |first2=J. |last3=Jarzembowski |first3=E.A. |year=2011 |title=New snakeflies (Insecta: Raphidioptera) from the Lower Cretaceous of the UK, Spain and Brazil |journal= Palaeontology |volume=54 |issue=2 |pages=385–395 |doi=10.1111/j.1475-4983.2011.01038.x|bibcode=2011Palgy..54..385J |doi-access=free }} and paleobotany,{{cite journal |last1=Channing |first1=A. |last2=Zamuner |first2=A. |last3=Edwards |first3=D. |last4=Guido |first4=D. |year=2011 |title=''Equisetum thermale'' sp. nov. (Equisetales) from the Jurassic San Agustin hot spring deposit, Patagonia: Anatomy, paleoecology, and inferred paleoecophysiology. |journal= American Journal of Botany |volume=98 |issue=4 |pages=680–697 |doi= 10.3732/ajb.1000211 |pmid=21613167|bibcode=2011AmJB...98..680C |doi-access=free |hdl=11336/95234 |hdl-access=free }} are the matching halves of a compression fossil, a fossil-bearing [matrix](/source/Matrix_(geology)) formed in [sedimentary](/source/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.[http://www.proz.com/kudoz/english_to_polish/archaeology/762880-slab_counter_slab.html ProZ] 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](/source/Fred_Hoyle) and applied physicist [Lee Spetner](/source/Lee_Spetner) in 1985 to declare that some ''[Archaeopteryx](/source/Archaeopteryx)'' fossils had been [forged](/source/Archaeopteryx), a claim dismissed by most palaeontologists.[https://books.google.com/books?id=gWtV-9zG8ycC&dq=fossil+%22Counter+slab%22&pg=PA3 ''New Scientist'' 14 March 1985] In its November 1999 edition, ''[National Geographic](/source/National_Geographic_Magazine)'' magazine announced the discovery of ''[Archaeoraptor](/source/Archaeoraptor)'', a link between dinosaurs and birds, from a 125 million-year-old fossil that had come from [Liaoning Province](/source/Liaoning_Province) of China. Chinese palaeontologist [Xu Xing](/source/Xu_Xing_(paleontologist)) 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: {{quote|a tale of misguided secrecy and misplaced confidence, of rampant egos clashing, self-aggrandizement, wishful thinking, naïve assumptions, [human error](/source/human_error), stubbornness, manipulation, backbiting, lying, corruption, and, most of all, abysmal communication.}} It was eventually determined that ''Archaeoraptor'' had been constructed from parts of an [Early Cretaceous](/source/Early_Cretaceous) bird ''[Yanornis martini](/source/Yanornis_martini)'' and a small dinosaur ''[Microraptor zhaoianus](/source/Microraptor_zhaoianus)''.[http://www.ifs.csic.es/sorites/Issue_20/colbourn.htm The Interpretive Mind] {{webarchive|url=https://web.archive.org/web/20100401195602/http://www.ifs.csic.es/sorites/Issue_20/colbourn.htm |date=1 April 2010}} 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](/source/Beijing_Natural_History_Museum). In the same year the [Institute of Vertebrate Paleontology and Paleoanthropology](/source/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](/source/Hyphalosaurus)'' is now the accepted name.[http://www.twoguysfossils.com/reptiles.htm Two Guys Fossils] {{webarchive|url=https://archive.today/20120914100749/http://www.twoguysfossils.com/reptiles.htm |date=14 September 2012}} ==References== {{Reflist|2|refs= {{cite book | last=Arnold | first=Chester A. | year=1947 | title=An Introduction to Paleobotany | url=https://archive.org/details/in.ernet.dli.2015.270777 | edition=1st | location=New York & London | publisher=McGraw-Hill Book Company | pages=[https://archive.org/details/in.ernet.dli.2015.270777/page/n22 14]–40 }} {{cite book | last1=Stewart | first1=Wilson N. | last2=Rothwell | first2=Gar W. |year=1993 | title=Paleobotany and the Evolution of Plants | edition=2nd | location=Cambridge | publisher=Cambridge University Press |isbn=0-521-38294-7 | pages=7–22 }} {{cite book | last1=Taylor | first1=Thomas N. | last2=Taylor | first2=Edith L. | year=1993 | title=The Biology and Evolution of Fossil Plants | location =Englewood Cliffs, NJ | publisher=Prentice Hall | isbn=0-13-651589-4 | pages=7–12 }} }} Category:Fossilization --- Adapted from the Wikipedia article [Compression fossil](https://en.wikipedia.org/wiki/Compression_fossil) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Compression_fossil?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.