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Table 4 Skull morphological description of different genera included within Placodontia

From: Dentition and feeding in Placodontia: tooth replacement in Henodus chelyops

Taxon

 

Paraplacodus

Placodus

Cyamodus

Placochelys

Psephoderma

Henodus

Premaxillary teeth

Number & Shape

3 long, procumbent and pointed

3 long, procumbent, spatulated and widely spaced

1 to 2 reduced and blunt

0

0

0

Maxillary teeth

Number & Shape

7 max. low and rounded with a central cusp

3–5 low and rounded (« bulbous») with a central cusp

2–3 hemispherical

3 flattened

2 flattened (posterior one is elliptical)

0

Size

Quite large

Quite large

Increasing rearwards

Increasing rearwards

Posterior one is larger

-

Palatine teeth

Number & Shape

4 low (3 posterior are rectangular)

3 quadrangular

2–3 circular or elliptical

2 flattened with a central cusp

2 Flattened with a central cusp

(posterior one is ovoid)

1 with a flat crown and covered by fine pits

Size

More large than maxillary teeth

Large

Very big (posterior one is the tallest)

Very big (posterior one is the tallest)

Very big (posterior one is the tallest)

Quite small

Rostrum

Shape

Wide

Wide

Narrow

Narrow, edentulous

Very thin and long, edentulous

Rectangular and wide, denticles

  1. The shape of the rostrum and the number, the shape and the size of teeth (premaxillary, maxillary, and palatine teeth) have been considered. The morphological descriptions come from v. Huene [18], Mazin [24], Reif and Stein [31], and Rieppel [26, 41]