Figure 13 in Fragilicetus velponi: a new mysticete genus and species and its implications for the origin of Balaenopteridae (Mammalia, Cetacea, Mysticeti)

Figure 13. Schematic diagram showing the phylogenetic relationships of Fragilicetus velponi gen. et sp. nov. and some morphological transformations as reconstructed from the cladistic analysis presented in the Supporting Information. A, phylogenetic relationships of Cetotheriidae, Eschrichtiidae, Fragilicetus gen. nov., and later Balaenopteridae. B, outlines of skulls in ventral view to show the morphology of the respective families. C, outlines of skulls in anterior view. D, schematic diagram showing dorsal skull architectures. Numbers in black circles correspond to typical balaenopterid character states. Numbers in white circles correspond to cetotheriid and eschrichtiid character states. Numbers correspond to the following: 1, protrusion of posterolateral corner of exoccipital (a, strong; b, slight); 2, posterior projection of postglenoid process of squamosal (a, no; b, yes); 3, squamosal bulges into the temporal fossa (a, yes; b, no); 4, supraorbital process of the frontal abruptly depressed from the interorbital region (a, no; b, yes); 5, shape of supraoccipital (a, triangular with narrow anterior border; b, triangular with broad anterior border; c, posterior portion widely expanded and lateral borders highly converging anteriorly); 6, articulation of rostrum and frontal (a, maxilla superimposed onto the interorbital region of the frontal, maxilla converging towards the midline posteriorly, premaxilla absent; b, premaxilla strongly superimposed onto the interorbital region of the frontal and maxilla reduced; c, maxilla superimposed onto the interorbital region of the frontal, premaxilla present); 7, supraorbital process of the frontal (a, gently descending or slightly depressed; b, abruptly depressed from the interorbital region of the frontal). Not to scale.