 Räuberei mit Vorlieben ? Side-preferences in predation on trilobites |
Jens 
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Hi to both of you ;-)
Andries is right, a good preparation is allways the key to a better understanding, especially when we deal with rare and not usual phenomens as injuries. Some preparations are more a crime than good craftsmenship;-)
At the moment I have not much time to discuss the interesting picture Ebonino provides us, but a short comment should be okay.
The moroccan Uralichas show a healed injury, the attack should happened some moultings back, but it's clear that something big was interested in this specimen and we can see, that also the left this of a couple of axial rings were obviosly damaged. This speaks for a very big mouth, probably a nautilid with a beak, but who one knows.
The 2nd specimen has a lost genal spine and show traces of wound recovery, the last moulting after the attac seems to be not far away.
I will join the discussion in the evening, now I must leave.
greetings,
Jens
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13.02.2011 13:09 |
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Jens
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ta-daaa....;-) I found something interesting.
I remembered me, that I read something about basal soft bodied cephalopods from the Cambrian and indeed, they exist.
http://www.nature.com/nature/journal/v46...ature09068.html
http://www.sciencedaily.com/releases/201...00526134142.htm
Nectocaris is one of the enigmatic fossils found in the Burgess Shale, who is now interpreted as a basal cephalopod with 2 tentacles. Together with the Lower Cambrian Petalilium and probably also Vetustovermis they form a own clade, but were formerly treaten as trilobitomorph arthropods.
There is nothing known about a beak, but the morphology of those animals make them to good candidates for predators. And their early occurence in the Cambrian fits well wih the known distribution of injured trilobites;-)
May be, we are close to a solution;-)
all the best,
Jens
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13.02.2011 16:31 |
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Andries
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Hi Jens,
a problem I see is that your soft bodied cephalopod is only 2 to 5 cm long.
Not realy big to worry about. ;o)
But what, if there are bigger ones 8o
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13.02.2011 17:28 |
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ebonino
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Andries
you are not wrong, is the same exposed in Germany (and in Liège last November during the Mineral & Fossil expo) and acquired from Italian Zoic Company.
Normally we have both, positive and negative, but I must confirm.
Well done Jens, also if I'm pretty sure that this old cephalopod (or supposed) was unable to predate (also small) trilobites with only two tentacles, it show that the original stem for cephalopod predator ( or phenomena of morphologic convergence?) was there.
May be that at the same time, undiscovered bigger paleo-squid swam freely chewing olenoids...
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13.02.2011 17:45 |
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juniper
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Hi Andries
That Uralichas fotography - did you take it at the Munich Fair last year (GeoFA 2010) ?
The specimen Pavel tried to talk-off the Italian dealer ? ("I'm only interested in the negative" =) )
If it is.... crazy small world ;)
Andries, dein Foto ...ist das der Uralichas aus München letztes Jahr? Bei dem Pavel ganz locker versuchte, dem italienischen Anbieter das Negativ abzuschwatzen =) ?
best regards
Klaus
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13.02.2011 20:17 |
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Andries
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yep, it is. 
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14.02.2011 13:59 |
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Jens
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Hi Andries,
mmh, it's difficult to get informations about the size without access to the full article. My attempt to measure the size on the small preview had a result of 7-8cm without the tentacles (with the assumption that the scale on the small picture is one centimetre). But in another explantion I find the information that the size is around two thirds of a adult little finger. Not big, but earlier interpretations of this aninmals claim out, that they should be predators, because of their free swimming life style (high energy demand)...
http://www.as.wvu.edu/~kgarbutt/Evolutio...nectocaris.html
It's also funny how strong the reconstructions and interpretation of a fossil animal change with the time.
http://www.as.wvu.edu/~kgarbutt/Evolutio...nectocaris.html
For me it's interesting, that they note, that free swimming animals are rarely preserved or trapped in the sediment.... It seems now, that they are small, but it's also possible that only small individual are preserved and the big ones not;-) It's can be the same problem like big trilobites, who are rarely preserved as whole specimens.
ciao,
Jens
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15.02.2011 10:09 |
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Andries
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Hallo Jens, hello Enrico,
a couple of weeks ago I read a nice book about burgess shale.
Inside was a picture which made me clear what we know, only the things we find. 8)
The picture shows the Fauna of the early Cambriam, known by hard-shelled bodies prior the discovery of Burgess Shale and the record of the soft-body fauna.
Burgess shale
This picture shows, how difficult it is to reconstruct a fauna.
And we don´t start to talk about micro organism, plants (several plants have been also found in Burgess shale), etc.
This is why it is always important that we don´t think that we know already everything.
greeting Andries
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15.02.2011 22:48 |
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Jens
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Hi all,
there is a interesting german article in the "scienceticker", about the doubts that Anomalocaris seems not to be a predator with a strong "bite" ability.
http://www.scienceticker.info/2010/11/03...biss/#more-8399
The mouth of Anomalocaris was, after the informations given in the article, allways open and after modellising not able to destroy a trilobite shell, also for the case, that the trilobite was in his soft ("butter crab") stage after molting.
But in this discussion nobody seems to look after the appendages of Anomalocaris. I've seen some reconstructions with sharp spines, and when the appedage was able to close (enrolling), then the spines should became the function of a saw. I think, Anomalocaris was still a predator, may be he suck the blood out of his prey, as some may think or he destroyed or may be, he only catched his prey and swallowed it whole. Who knows.
all the best and we see us soon in Frankfurt.
Jens
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18.02.2011 11:55 |
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