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From my limited rookie knowledge, birds follow the same rule as mammals as far as bone growth and reaching an adult stature and don't continually grow until death.
Richard Klein did a lot of work on tortioses and average size change through time as an indicator of human population density during the MSA-LSA... i.e. more people, more predation, smaller tortoises. I think he (or others) did the same calculations for limpets.
A European/historical faunal collection I analyzed in South Africa had a fair number of tortoises. It included some subadults, but were mostly adult (ends of long bones would be dense and smooth like a mammal's articular surface while the younger were porous and soft). I noticed a great variability in size of certain carapace/plastron fragments which show tortoises of different sizes and possibly different ages if tortoises do grow continuously. Also assuming a population would grow at a relatively standard rate. Being the deposit is strictly dated to between 1740-1761, it doesn't seem to speak to increased human predation, but perhaps they are a reflection of the range of sizes available on the local landscape. Adam Heinrich
From: Greg Campbell <[log in to unmask]>
Reply-To: Greg Campbell <[log in to unmask]>
To: [log in to unmask]
Subject: [ZOOARCH] continuous growth til death
Date: Thu, 21 Sep 2006 20:28:47 +0100
Dear Zooarchers: I have been looking at growth patterns in modern and archaeological shells (especially limpets an sea urchins) for a while now, and the typical pattern is for growth to be continuous through life, but to slow over time, so the average size for a given age in a given population gradually approaches an upper limit. Some of you may know this model as the von Bertalannfy curve, or similar equations. I know that this works for most marine invertebrates, and for fish. I also know that it does not work for domesticated mammals (including us!), which undergo long-bone epiphyseal fusion and cannot therefore increase in stature. So, which organisms continuously grow until death? Is there a general rule?For example, do marine mammals (pinnipeds, cetaceans, dugongs) grow continuously? Do palae-arctic mammals? Do tropical mammals, like elephants? (this might imply a fairly narrow temperature range means you can grow continuously.)Is there a general rule for birds? I know chickens stop growing, but is it general in the Aves, or just the domesticated ones?Ho about reptiles and amphibians? I know some dinosaurs grew continuously (annual rings in the long-bones) but is it true for all simple terrestrial vertebrates? I am especially interested in turtles, as some are using turtle size diminution as an indicator for human population density increase in the Stone Age.Greg Campbell