oilshale Posted March 5, 2011 Share Posted March 5, 2011 (edited) The Thylacocephala (from the Greek thylakos, meaning "pouch", and cephalon meaning "head") is a recently recognized extinct group of uncertain, but probably crustacean, affinity, comprising fossils formerly assigned to many different crustacean groups. Of the features which could prove crustacean affinities, the arrangement of mouthparts would be the easiest to find in the Thylacocephala. The literature features some mention of such a head arrangement, but none definitive. These fossils were very often assigned to the phyllocarids despite an apparent lack of abdomen and appendages. The Thylacocephala typically possess a large, laterally flattened carapace that encompasses the entire body, three pairs of long raptorial (predatory) appendages and the abdomen bears a battery of small swimming limbs. The compound eyes tend to be large and bulbous, and occupy a frontal notch on the carapace. The earliest Thylacocephalan fossil is thought to date from the lower Cambrian, while the class has a definite presence in Lower Silurian marine communities. As a group, the Thylacocephala survived to the Upper Cretaceous. This is a reconstruction of Clausocaris with prey from the Upper Jurassic of Solnhofen. The oldest member of this group seems to be Zhengecaris from the Early Cambrian Maotianshan Shale fauna. Stigall and Hendricks described the first Devonian Thylacocephala Concavicaris from Grand Gorge, Schoharie County, New York. Concavicaris georgeorum, described by Schramm, is from the Mazon Creek formation. So far, three genera are known from Solnhofen: Clausocaris, Dollocaris and Mayrocaris. Clausocaris lithographica is the largest and can reach 6cm – Dollocaris michelorum Polz 2001 with 1,5cm is the smallest of these three. Here is a picture of Clausocaris lithographica - the specimen is a bit faint though relatively well preserved. This Thylacocepala here seems to be neither Dollocaris nor Mayrocaris and could be a new genus to Solnhofen. First report of a concavicarid interior (crustacea: thylcocephala) from the Devonian of North America On Mazon Creek Thylacocephala The Cambrian Origin of Thylacocephalan Arthropods Edited March 6, 2011 by oilshale 2 Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC). Link to comment Share on other sites More sharing options...
piranha Posted March 5, 2011 Share Posted March 5, 2011 Outstanding ... Thanks for posting Thomas !! Link to comment Share on other sites More sharing options...
pleecan Posted March 5, 2011 Share Posted March 5, 2011 Excellent posting Thomas! Link to comment Share on other sites More sharing options...
Auspex Posted March 5, 2011 Share Posted March 5, 2011 Cryptic, rare, and wonderful! I have never heard of them before now. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
RCFossils Posted March 5, 2011 Share Posted March 5, 2011 Great specimens Thomas! I have found a few of these in the Essex (marine) portion of the Mazon Creek deposit. I have also collected some very large specimens in black shale. The site has fossils similar to the Mecca Fauna of Indiana. They are really bizzare looking critters. Link to comment Share on other sites More sharing options...
frenchtrilobite Posted March 6, 2011 Share Posted March 6, 2011 Very interesting ! NICE !! My new website : http://www.trilobite.fr Link to comment Share on other sites More sharing options...
Aramon Posted March 6, 2011 Share Posted March 6, 2011 These are really strange forms... Thanks for your interesting post! Link to comment Share on other sites More sharing options...
oilshale Posted January 27, 2013 Author Share Posted January 27, 2013 (edited) This is a new Thylacocephala in my collection: Mayrocaris bucculata Polz, 1994. Comes from Zandt, a Solnhofen Formation location famous for its finely grained limestone. Edited January 27, 2013 by oilshale 1 Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC). Link to comment Share on other sites More sharing options...
Plantguy Posted January 28, 2013 Share Posted January 28, 2013 This is a new Thylacocephala in my collection: Mayrocaris bucculata Polz, 1994. Comes from Zandt, a Solnhofen Formation location famous for its finely grained limestone. Wow Thomas. another great addition to add to all your fabulous Solnhofen material! what a strange creature! Regards, Chris Link to comment Share on other sites More sharing options...
oilshale Posted September 1, 2016 Author Share Posted September 1, 2016 There are three genera known from Solnhofen: Clausocaris, Dollocaris and Mayrocaris; one additional species in my collection is still undescribed. Dollocaris michelorum Polz, 2001 - with 1,5cm the smallest of these three - was still missing in my collection. Now I finally got one: Dollocaris michelorum Polz, 2001 - carapace size is less than 1 cm (.4") Can be best seen under UV light. 2 Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC). Link to comment Share on other sites More sharing options...
Fossildude19 Posted September 1, 2016 Share Posted September 1, 2016 Excellent fossils, and informative post. Thanks Thomas! Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
marguy Posted September 1, 2016 Share Posted September 1, 2016 3 species of Thylacocephala were discovered in french Callovian lagerstatte , La Voulte sur Rhone (Ardèche) You can see pictures here: http://www.apgn.fr/apgn/ressources/fic_66_Biot_Caze.pdf ( pages 10 and 33 ) http://www-personal.umich.edu/~wstoddar/voultesurrhone.pdf (p 17- 18) and a recent publication about exceptional preservation of the structure of the eye: http://www.nature.com/ncomms/2016/160119/ncomms10320/full/ncomms10320.html Marguy 1 Link to comment Share on other sites More sharing options...
oilshale Posted September 1, 2016 Author Share Posted September 1, 2016 Merci beaucoup marguy, c'est très interessant! La Voulte est un gisement très spécial. Thomas Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC). Link to comment Share on other sites More sharing options...
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