Polyonyx gomesi, Santos & Moratalla & Royo-Torres, 2009

Santos, Vanda F., Moratalla, José J. & Royo-Torres, Rafael, 2009, New sauropod trackways from the Middle Jurassic of Portugal, Acta Palaeontologica Polonica 54 (3), pp. 409-422 : 411

Polyonyx gomesi isp. nov.

Figs. 3–5 .

Etymology: In memory of Jacinto Pedro Gomes (1844–1916), curator of the Museu Mineralógico e Geológico da Escola Politécnica (Lisbon, Portugal), the first naturalist to study (in 1884) dinosaur tracks in Portugal ( Gomes 1916).

Holotype: A trackway in situ (142 m long with 94 consecutive manus−pes print sets; reference G5) at the Galinha tracksite classified as a Natural Monument— Monumento Natural das Pegadas de Dinossáurio da Serra de Aire (Serra de Aire Dinosaur Tracks Natural Monument), Portugal. In MNDPDSA centre there is a cast with a sequence of a left manus print, two pairs of manus−pes prints and a right pes print (reference MNDPDSA−G5).

Type horizon: Serra de Aire Formation, close to the Bajocian–Bathonian boundary, Middle Jurassic ( Azerêdo 1993; Azerêdo et al. 1995).

Type locality: Galinha tracksite, Municipal area of Bairro, Serra de Aire, West−Central Portugal.

Diagnosis.—Wide gauge sauropod trackway revealing low heteropody (manus−pes area ratio 1:2) and two autapomorphies: (1) asymmetric manus prints with large digit I marks oriented in a medial direction with a large, posteriorly oriented, triangular claw mark, and impressions of digits II, III, IV and V; (2) pes prints with four claw marks: claws I–II with an anterior orientation, and III–IV laterally oriented. Manus digits II–V show a slightly bent arrangement.

Description.—This trackway is a wide gauge sauropod trackway with an inner trackway width 1.2 times the footprint width (Wit/Pw; see Tables 1 and 2, Fig. 5 ). The manus prints are wider than long with a rounded lateral edge (digit mark V), a large digit I mark oriented in a medial direction and with a large, posteriorly oriented, triangular claw mark I, and impressions of digits II–IV ( Fig. 4A ). Other manus prints of trackway G5 show digit II–IV marks at the anterior margin. The pes prints are longer than wide, oval shaped, and have four claw marks (claws I–II with an anterior orientation, and III–IV laterally oriented). The ichnospecies shows low heteropody (the pes area is about twice the manus print area). Occasionally, the manus print centres are closer to the trackway midline than the pes print centres. Both the manus and pes prints are rotated outward relative to the trackway midline. Considering the direction of the manus and pes print width in relation to trackway midline, the rotation values for the manus prints are vary from 25° to 50° and the pes print values from 25° to 42°. With respect to the pes print length, the outer trackway width is 2.7 times wider (Wot/Pl, Table 2), the manus−pes distance is 0.3–0.6 times longer (Dmp/Pl, Table 2), and the stride length is 3.4 times longer (λ/Pl, Table 2). The glenoacetabular distance is three times the pes print length (Dga/Pl, Table 2) and 1.1 times the outer trackway width (Dga/Wot, Table 2). The pace angulation value is about 95°.

Stratigraphic and geographic range.—Bajocian−Bathonian of West−Central Portugal.

Figures

Fig. 3. Long sauropod trackways at the Galinha dinosaur tracksite (Bairro, Serra de Aire, West−Central Portugal). Trackway G1 is 147 m long and trackway G5 is 142 m long. Modified from Santos (2003).

Fig. 4. Polyonyx gomesi igen. et isp. nov., sauropod manus and pes prints from trackway G5 at the Galinha dinosaur tracksite (Bairro, Serra de Aire, West−Central Portugal). A. Outline (A1) and photograph (A2) of a left manus print. B. Outline (B1) and photograph (B2) of a right pes print. Modified from Santos (2003).

Fig. 5. Segment of G5 sauropod trackway at the Galinha dinosaur tracksite (Bairro, Serra de Aire, West−Central Portugal): Polyonyx gomesi igen. et isp. nov. Modified from Santos (2003).