Heterodontus mexicanus, Taylor & Castro-Aguirre, 1972

3.1.5 | Heterodontus mexicanus View in CoL

A small heterodontid egg case ( 75.4 – 83.6 mm ECL), lateral keels making 2¼ rotations from anterior to posterior ends; egg case body surface smooth, keel surfaces with weak striations; anterior margin broad and slightly S-shaped when viewed from anterior plane; widest at midportion, gradually tapering posteriorly from midportion; keel base to keel apex space at midportion moderate (11.3% – 13.1% ECL); keels moderate (8.4% – 12.0% ECL), thick, robust, and ridged, projecting outward from egg case body and asymmetrically T-shaped (Figure 2e), tapering into long curling tendrils at posterior end. Color brown to golden brown when preserved (Figure 7), with deposited egg cases appearing yellowish-brown to golden brown.