. Bulletins of American paleontology. Mexican ammonites: Verma & Westermann 217 70r 50 30 U (mm) 20-. '-^^ â¡ Holotype â New Topotypes 50 50 100 D (mm) 200 Text-fig. 20. â Scatter diagram of umbilical -width (U) vs. diameter (D) for Kossmatia bijurcata [9 + ? 5 ]⢠The inner whorls of the macro- conchs (continuous lines) cannot be measured without damaging the speci- mens, but it appears that they v,-ould fall within the range of variation of the microconchs (dashed lines). The septal suture (Text-fig. 17B) shows a deep complicated E, a bipartite E/L saddle with deep incision, and a less d
. Bulletins of American paleontology. Mexican ammonites: Verma & Westermann 217 70r 50 30 U (mm) 20-. '-^^ â¡ Holotype â New Topotypes 50 50 100 D (mm) 200 Text-fig. 20. â Scatter diagram of umbilical -width (U) vs. diameter (D) for Kossmatia bijurcata [9 + ? 5 ]⢠The inner whorls of the macro- conchs (continuous lines) cannot be measured without damaging the speci- mens, but it appears that they v,-ould fall within the range of variation of the microconchs (dashed lines). The septal suture (Text-fig. 17B) shows a deep complicated E, a bipartite E/L saddle with deep incision, and a less deep trifid L; some of the complexity may have been lost during preparation with acid. Remarks. â This species is clearly distinguished by its large size, the stout ribs of the outer whorls, and the consistency of bifurcation just above mid-flank. The variability in rib thickness and spacing and the absence of complete specimens appear to be the reason for the taxonomic "splitting" by Aguilera {in Castillo and Aguilera, 1895). Thus, his ^^Kossmatia ; is merely an ad- vanced growth stage of K. bijurcata. This ontogenetic variability. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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