McHorse Posted March 4, 2016 Share Posted March 4, 2016 Hi all, I was in a local fossil store having a yarn to the owner about his Glen Afric Crab fossils. When I noticed that one of his crabs had a larger left pincer than the right. When I pointed this out to him he acted very surprised and told me that in all his years he has never seen a left handed crab fossil (a larger left pincer than the right) and that this crab must be extremely rare. Is he pulling my pincer or is it true that left handed crabs are extremely rare or rarer? Regards. Link to comment Share on other sites More sharing options...
Wendell Ricketts Posted March 4, 2016 Share Posted March 4, 2016 Do a Google search for "handedness in crabs" and you'll have more info than you know what to do with. I didn't spend much time reading, but it would appear that the predominant claw in heterochelous species (and that's a great word I never knew before) is much more likely to be the right. W 2 _________________________________ Wendell Ricketts Fossil News: The Journal of Avocational Paleontology http://fossilnews.org https://twitter.com/Fossil_News The "InvertebrateMe" blog http://invertebrateme.wordpress.com Link to comment Share on other sites More sharing options...
Ludwigia Posted March 4, 2016 Share Posted March 4, 2016 This one managed to win the FOTM a few years ago. 1 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
caterpillar Posted March 4, 2016 Share Posted March 4, 2016 Here some example http://www.paleotheque.fr Link to comment Share on other sites More sharing options...
aplomado Posted March 4, 2016 Share Posted March 4, 2016 Cool! Link to comment Share on other sites More sharing options...
RJB Posted March 5, 2016 Share Posted March 5, 2016 Not sure how 'rare' a left handed crab is? Ive seen a few in other species before. I just assumed that they lost the right pincer in a fight while younger and grew a new one, now being the smaller 'hand'. RB Link to comment Share on other sites More sharing options...
Mombo Posted March 5, 2016 Share Posted March 5, 2016 Typically what happens in crabs is that if they were to lose one claw for whatever reason (say from a predator), they can regrow that lost limb. Unfortunately, the downside to this ability is that the appendage will be much smaller than their lost appendage. This would give the impression of "right" or "left" handedness. Most likely what this fossil represents is something pretty common in the animal kingdom, but nevertheless is still incredibly interesting. Many species of lizard have a similar ability when it comes to their tails. If a predator were to latch onto the tail, the lizard can actually lose it to make their getaway. The nerve endings in the lost tail will still fire and make the tail look like a wiggling creature. The lizard can regrow this lost tail, but, much like the crab claws the tail will generally be smaller than the lost tail. 1 Link to comment Share on other sites More sharing options...
amour 25 Posted March 5, 2016 Share Posted March 5, 2016 Mombo yo da the man, and don't let Ron in on those left handed fellows, otherwise he will scour the earth for them. Jeff Link to comment Share on other sites More sharing options...
RJB Posted March 5, 2016 Share Posted March 5, 2016 You one funny guy Jeff. Ha! RB Link to comment Share on other sites More sharing options...
crabfossilsteve Posted March 6, 2016 Share Posted March 6, 2016 I don't think left handed crabs are all that rare. There is probably some ratio, like us. I have a fair number of lefties in my collection. Not exactly sure what happens when a claw is lost and regrows, whether it regrows the same kind of claw (that makes sense to me). In heterochelate crabs, there are two different types of claws, generally one crushing and one tearing type in which the teeth and claw structure are different. Generally, the bigger claw is the crusher. 1 Link to comment Share on other sites More sharing options...
caterpillar Posted March 6, 2016 Share Posted March 6, 2016 (edited) Im my Xanthilites outcrop, I find 2% of left handed crabs But in Zanthopsis outcrop, I've never found one with several hundred crabs collected. Alex, can you confirm? Zanthopsis and Xanthilites lost also their claws Edited March 6, 2016 by caterpillar 1 http://www.paleotheque.fr Link to comment Share on other sites More sharing options...
MB Posted March 6, 2016 Share Posted March 6, 2016 Yes, there are, but in lesser proportion than in your "Xanthilites" outcrop. BTW you can call your macrodactylus as Litoricola. In an accepted paper, they are transferred provisionally to this genus. 2 http://www.mbfossilcrabs.com/ Link to comment Share on other sites More sharing options...
caterpillar Posted March 7, 2016 Share Posted March 7, 2016 Ok, I knew that but I was not sure. Thanks Can you send me the paper, please? http://www.paleotheque.fr Link to comment Share on other sites More sharing options...
crabfossilsteve Posted March 7, 2016 Share Posted March 7, 2016 For what its worth, although I can't quantify the percentage, I have found left handed crabs at a higher percentage in Branchioplax and Panopeus specimens. There is lefty Branchioplax eBay right now..ha ha. Perhaps different crab genera have different percentages of left handedness. Link to comment Share on other sites More sharing options...
FossilDAWG Posted March 7, 2016 Share Posted March 7, 2016 I realize this is very indirect evidence, but it has been suggested that some snails (such as Conus adversarius) evolved sinistral (counterclockwise) coiling as a defense against crab predation. This would make sense only if a majority of co-occurring crabs had the larger crusher claw (used the break open the shell starting from the lip) on the right. Don Link to comment Share on other sites More sharing options...
6ix Posted March 16, 2016 Share Posted March 16, 2016 Tinbum's first crab.. Link to comment Share on other sites More sharing options...
RJB Posted March 17, 2016 Share Posted March 17, 2016 That one super cool 'left hander' 6ix!!! RB Link to comment Share on other sites More sharing options...
FossilDAWG Posted March 17, 2016 Share Posted March 17, 2016 Don Link to comment Share on other sites More sharing options...
amour 25 Posted March 18, 2016 Share Posted March 18, 2016 Holy snarge ,looks like almost prepared already. Jeff Link to comment Share on other sites More sharing options...
6ix Posted March 22, 2016 Share Posted March 22, 2016 Yeah, the boy was lucky with that one. Its very soft, you can peel the mudsone away with a fingernail... Link to comment Share on other sites More sharing options...
MB Posted March 22, 2016 Share Posted March 22, 2016 Ok, I knew that but I was not sure. Thanks Can you send me the paper, please? The paper is "in press" and in few weeks will be published online. I'll let you know. 1 http://www.mbfossilcrabs.com/ Link to comment Share on other sites More sharing options...
caterpillar Posted March 22, 2016 Share Posted March 22, 2016 Ok, thanks http://www.paleotheque.fr Link to comment Share on other sites More sharing options...
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