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Here are two links to posts dealing with how to post pictures on Black River Fossils forums.
1. How to Post Pictures on Black River Fossils Forums by ditchweezil
2. How to Post Pictures on Black River Fossils Forums by Daryl
I have a little over 6,000 Galeocerdo Contortus (aka physogaleus) tiger shark teeth that I've colelcted from Calvert Cliffs, MD over the last 12 years. After embarking on a study some time ago, I had come back to a thought I had years ago, that is, where are all the juvenile tiger shark teeth? Besides the G. contortus variety, I also have several thousand G. aduncus tiger shark teeth as well. The average size of these is around .75", and I have found several "juvenile" or small aduncus teeth. However, when it comes to the contortus teeth, honestly, I don't think I have a single "juvenile" or small/tiny contortus tooth.
I've never found a small contortus at Lee Creek either. I don't mean posterior or "short" either, I do have plenty of posterior teeth where the crown is curved all the way over onto the shoulder, but the tooth is still 1/2" long or so. I don't know how big the contortus sharks were at birth, but I would think that there has to be juvenile teeth somewhere (deeper waters?).
I have juvenile specimens of practically every other shark tooth species (mako, meg, snad tiger, grey, nurse, hemi, etc.), just no baby contortus teeth!
Daryl.
I have wondered about that myself. I think they might have had their pups nearshore, in extremely shallow water, maybe similar to the mangrove swamps in Florida. There are several shark species that pup in shallow water today. Nurse sharks and hammerheads are two good examples.
It dawned on me after I posted this thread that out of a few hundred cowshark teeth, I only have three or four that I would consider to be juvenile teeth.
I would be really interested in seeing some examples of juvenile contortus teeth if anyone has any. Anything around .25" would be considered juvenile to me since the average size contortus is also around .75".
I did a little searching through my "caste" of teeth and found no recognizable juvenille teeth either. For comparison, juvenille makos, megs, etc. were relatively plentiful. I have C. auriculatus juvenille teeth as well from the cement mines.
Interestingly, I have some SC G. Contortus and found no juvenilles. Maybe the shark's nursing grounds are in a different place? I may dig into modern tiger shark studies to see if there is any data. Better yet, lets plan a BRFC trip to Hawaii to study this!!
DW & DF, thanks for checking your collections, and DW - for the pics!
DW, I have plenty of each of those tooth positions you have pictured, I believe these are smaller because they are para-symphyseal or symphyseal type teeth, or 1st anterior, just like these positions in the mdoern cuvier shark are much smaller than the rest of the teeth in the jaw. I also have some teeth that I nicknamed "nubby" teeth, because the root is fat and bulbous, has a short stout crown, and very little enamel on the shoulders. These teeth are all in the 1/4" range as well, but I've never been able to determine if they belong to tigers such as a symphyseal contortus, or perhaps a symphyseal carcharhinus of some sort.
It's interesting that I do have plenty of juvenile G. aduncus teeth along with the tons of adult size aduncus and contortus teeth Does this mean that aduncus wasn't afraid to birth its young in the same waters where contortus roamed? As far as tooth numbers goes, I have a little over 6,000 contortus teeth, but only half that much (~3,000) aduncus teeth. Don't know how typical that is for other collecting areas, but I know I do tend to find more contortus at Lee Creek than I do aduncus teeth there. Either contortus outnumbered aduncus, or maybe contortus just shed its teeth more frequently, or ...
You know, any reason to go through my shark tooth collection is a good one. Thanks for the excuse .
I find G. aduncas in the same proportion to G. contortus around Summerville, and just like you I have many juvenile aduncas but (apparently) no juvenile contortus. It seems very strange to me, too, that as much as I have collected (more than 25 years!) I don't have a single obvious juvenile specimen. Somewhere, somebody is saying to themselves "Why can't I find a decent sized tiger shark tooth?? All I ever find are these puny things!"