Loefer and Sedberry: Life history of Rhtzopnonodon terraenovae off tfie southieastern United States 



79 



O 



300 



250 - 



200 - 



150  



100 - 



50 - 



2«^°^ 



n = 290 



200 



300 400 500 600 700 800 900 



Precaudal lengtti (mm) 



Figure 3 



Relation of clasper and siphon sac length to precaudal length for male 

 R. terraenovae; (•) represents individuals with uncalcified claspers; 

 (O) represents individuals with fully calcified claspers. 



Females: W, = e(-is.62)pcL(3M) 



(/•^'=0.99, P<0.0001, /i=458); 



Males; w = e(-i8.i8.pcL'2 96i 



(?-^'=0.99, P<0.0001. n=454). 



where W, = total body weight. 



Aging was attempted on 890 specimens, 812 of which 

 were aged without elimination. Agreement between the 

 first and second counts conducted by the primary reader 

 was 66%, with 91% within one increment, and 99% within 

 two. Those sections that showed disagreement between 

 the first and second reading (n=303) were counted a third 

 time, and 96% agreed with one of the first two readings. 

 The remaining 4% (12 specimens) were excluded from the 

 analysis. Agreement between readers was 72%, with 95% 

 within one increment and 99%. within two. Vertebrae for 

 which counts did not agree between readers (246 out of 

 878) were re-examined by both readers simultaneously. 



A concurrent age could not be reached on 66 vertebrae, 

 which were eliminated from the study. The lAPE between 

 the final readings of the primary reader and the initial 

 readings of the secondary reader was 7.4%. Size-frequency 

 distributions of the discarded individuals (data not shown) 

 closely matched those of the raw data set and did not indi- 

 cate the elimination of a large number of individuals from 

 any age class during the aging process. 



Mean relative marginal increments for age classes 1+ 

 through 7+ combined demonstrated a minimum in July 

 (Fig. 8). The O-i- age class was excluded from this analysis 

 to ensure that growth from the birth mark did not affect 

 the results. Frequency distributions of focus-to-increment 

 measurements for ages 0+ through 7+ demonstrated single 

 modes for all annuli in each age class for both males and 

 females (Fig. 9). 



Most R. terraenovae were found to have an increment in 

 the intermedalia and an associated change in the angle of 

 the corpus calcareum. which is similar to the birth mark 



