Fig 1.
Dixonanogmius sp. from the Middle-Late Santonian Los Temporales locality (CPC-2837) (A) and from the Cenomanian San Carlos quarry (CPC-2838 and CPC-2836) (B and C). T. formosa from the Turonian Mesa Las Tablas quarry in southern Coahuila (CPC-2835) (D). All scales 50 mm.
Fig 2.
Preservational stages of the dorsal fin of T. formosa.
Disarticulated dorsal fin (CPC-2892) (A). Folded dorsal fin classified as ‘not spread’ (ns) within a range of 0°—20° (CPC-2841) (B). Middle spread dorsal fin (ms) within 21° to 40° (CPC-2948; REG2544 PF48) (C) and full spread (fs) dorsal fin (>41°) (CPC-2839) (d). All scales 50 mm.
Fig 3.
Body length of T. formosa in relation to body depth (A). Diamond-shaped individuals are deeply keeled and twice as long as wide, in contrast to torpedo-shaped individuals that are three times longer than wide with a more streamlined body outline (B).
Fig 4.
Body shape types documented in T. formosa.
Diamond-shaped individuals are deeply keeled (A—C) while torpedo-shaped individuals show a streamlined body outline (D—F). The specimen collection numbers are placed inside each shape.
Fig 5.
Diamond-shaped, torpedo-shaped and disarticulated individuals of T. formosa in percentage.
Fig 6.
Size range distribution of 143 individuals of T. formosa from Vallecillo correlated to both body shape types.
Torpedo-shaped individuals are marked in red and diamond-shaped specimens in green. Disarticulated individuals are presented in blue and ambiguous individuals in yellow.
Fig 7.
Scales of T. formosa from Vallecillo (CPC-2824) (A) in comparison to Dixonanogmius sp. from San Carlos (CPC-2836) (B).
All scales 50 mm.
Fig 8.
Completeness (A) and articulation (B) of T. formosa from Vallecillo in percent of the total number of individuals. Completeness stages differentiated here (Fig. 8A) include complete (c), nearly complete (nc), partially complete (pc), mostly incomplete (mic) and incomplete (in) specimens. Articulation stages differentiated (Fig. 8B) include articulated (a), nearly articulated (na), partially articulated (pa), mostly disarticulated (md) and disarticulated (d) individuals.
Fig 9.
Preservation of the dorsal (A), anal (B), pectoral (C) and pelvic fins (D) of T. formosa, in percent of the total number of individuals.
Disarticulated (d), not spread (ns), mostly spread (ms), fully spread (fs), not preserved (np) and preserved.
Fig 10.
Preservation of the vertebral column in T. formosa, in percent of the total number.
Disarticulated (d), no break (nb), break in head region (hr), break in tail region (tr), break in head and tail region (ht).
Fig 11.
Reconstruction of the dorsal fin of T. formosa.
Fossil outline as identified in CPC-2839 and CPC-2948; REG2544 PF48 with semi-erected dorsal fin (A and C) in comparison to its modification (B and D) with erected dorsal fin. Schematic reconstruction of the dorsal and anal fin including a membrane between the fin rays (E) and scale color as suggested by Giersch (2014). Both scales 50 mm.
Fig 12.
Mouth preservation of T. formosa, in percent of the total number.
Disarticulated (d), closed (cl) and open (o).
Fig 13.
Disarticulated T. formosa (CPC-2833).
The carcass disintegrated on the seafloor without bone dispersal caused by scavengers or currents. A phase of flotation is excluded. Scale 100 mm.
Fig 14.
Retraction of the unpaired fins of T. formosa behind lateral plates (A and B) (CPC-2856 and CPC-2885). Reconstruction of the skeletal elements found in the unpaired fins (C). All scales 50 mm.
Fig 15.
Preservation of the unpaired fins in T. formosa.
A skin shadow (CPC-2832 and CPC-2883) (A and B) illustrates the sulcus to retract the dorsal and anal fin. Retracted dorsal fin without overlapping fin rays (CPC-2865) (C). Parallel arrangement of the dorsal fin rays (CPC-2960; REG2544 PF220) (D). Collective reaction of the fin rays similar to a fan indicating an intact membrane between the lepidotrichia (CPC-2902 and CPC-2871) (E and F). All scales 50 mm.