Dromaeosauridae Matthew and Brown, 1922

Torices, Angelica, Currie, Philip J., Canudo, Jose Ignacio & Pereda-Suberbiola, Xabier, 2015, Theropod dinosaurs from the Upper Cretaceous of the South Pyrenees Basin of Spain, Acta Palaeontologica Polonica 60 (3), pp. 611-626 : 619-620

publication ID	https://doi.org/ 10.4202/app.2012.0121
persistent identifier	https://treatment.plazi.org/id/0C1C87B8-937D-FFD0-F732-595FFC47F922
treatment provided by	Felipe
scientific name	Dromaeosauridae Matthew and Brown, 1922
status

Treatment

Dromaeosauridae Matthew and Brown, 1922 Genus Dromaeosaurus Matthew and Brown, 1922

Type species: Dromaeosaurus albertensis Matthew and Brown, 1922 ; Red Deer River , Campanian .

? Dromaeosauridae indet.

2002 Dromaeosauridae indeterminate 2; Torices 2002: 141.

2004 cf. Dromaeosauridae morphotypes 2, 5 and 6; Torices et al. 2004: 73.

2005 Maniraptoriforme indet.; Canudo et al. 2005: 34.

Material.— Four specimens: MPZ2004 View Materials /6 from Blasi ( Arén Formation , upper Maastrichtian ); MCNA 14622 View Materials from Laño lateral equivalent of Sedano Formation , upper Campanian – lower Maastrichtian); DPM-FON6-T2 from Fontllonga 6 Tremp Formation , lower Maastrichtian ); DPM-FIG2-T1+T2 from Figuerola 2 ( Tremp Formation , upper Campanian) ( Figs. 3B, C View Fig , SOM: Table 1) .

Description.—The measurements of the teeth of indeterminate dromaeosaurids vary from a minimum crown height of 3.4 mm (as estimate from a broken specimen) to 17.5 mm, FABLs of 2.6 to 16 mm, and basal widths between 1.3 and 5.8 mm. Crown shapes in lateral or medial views correspond to two types: (i) biconvex borders or (ii) a convex anterior border and a straight posterior one. These laterally compressed teeth have denticulate carinae. Denticle densities vary between 3.5 to 8.1 anterior denticles/mm and 2.5 to 4.9 mm posterior denticles/mm. The denticles are rectangular, slightly rounded and chisel-like ( Currie et al. 1990).

The indeterminate dromaeosaurid from Laño consists of only the tip of a tooth that has a convex anterior border and straight posterior one. Denticle densities are 8.1 anterior denticles/mm and 4.9 posterior denticles/mm.

The specimen from Fontllonga 6 is biconvex in morphology and has large denticles with a density of 3 posterior denticles/mm. The tooth from Figuerola 2 lacks enamel, although it is possible to see traces of the denticles and measure their density (2.5 posterior denticles/mm).

The teeth from Blasi have convex anterior borders and straight posterior ones. Their anterior denticle densities vary between 3.5 and 5 denticles per millimeter, whereas their posterior denticle densities vary between 2.9 and 3 denticles/mm.

Discussion.—All Dromaeosaurus teeth in the collections of the Royal Tyrrell Museum of Palaeontology and those from the holotype (AMNH 5356) of Dromaeosaurus albertensis Matthew and Brown, 1922 were measured. The height of the teeth of this sample varies between 5.33 and 26 mm, FABL varies between 2.17 and 8.83, and basal width ranges from 1.67 to 9.17. Anterior denticle density is 1 to 8.75 denticles/ mm, whereas posterior denticle density is 1 to 6.25 denticles/ mm. The measurements of the teeth from the Pyrenean sample fall within the ranges of these measurements and those described in the literature ( Currie et al. 1990; Baszio 1997; Sankey et al. 2002). The rectangular, chisel-like morphologies of the denticles match those described for dromaeosaurids ( Figs. 4 View Fig , 5 View Fig ).

The discriminant analyses suggest that all teeth fall in the Dromaeosauridae ; two of them are grouped with Dromaeosaurus teeth and one is placed with? Pyroraptor teeth (SOM: Table 2). The last tooth was not identified as Pyroraptor because its denticles resemble the taller, narrower ones of dromaeosaurids than the lower, broader ones of Pyroraptor .

It should be noted, however, that there is a diagnostic characteristic of Dromaeosaurus that is not found in any of the Spanish teeth. The anterior carina of each tooth of Dromaeosaurus extends along the midline from the apex to mid-height of the tooth, and then twists onto the lingual surface ( Currie et al. 1990). The absense of this feature in the Spanish teeth suggests that they cannot be assigned to the genus Dromaeosaurus . They are designated here as indeterminate dromeosaurid teeth.

Genus Pyroraptor Allain and Taquet, 2000

Type species: Pyroraptor olympius Allain and Taquet, 2000 , Provence.

? Pyroraptor olympius Allain and Taquet, 2000

2002 Dromaeosauridae indeterminate 3; Torices 2002: 141–143.

2004 cf. Dromaeosauridae indeterminate Morphotype 3; Torices et al. 2004: 73.

Material.—Four teeth ( MCNA 14623–14626) from the Laño (lateral equivalent of Sedano Formation, upper Campanian– lower Maastrichtian); one (DPM-MON-T1) from Montrebei (Tremp Formation, upper Campanian–lower Maastrichtian) ( Figs. 2B, C View Fig , 3A View Fig )

Description.—The teeth assigned to? Pyroraptor olympius are laterally compressed with convex anterior borders and concave posterior ones. Their heights vary between 3.8 and 8 mm, FABLs between 2.5 and 5.4 mm, and basal widths range between 1.4 and 2.4 mm. Anterior denticle densities vary between 8 and 9.8 denticles/mm and posterior denticle densities are 6 to 6.5 denticles/mm. The denticles are square.

Three of the teeth were found in situ within a dentary bone fragment and the other one was found isolated but in association with the dentary fragment ( MCNA 14623–14626). In this fragment, it can be seen that the interdental plates are fused together, which is characteristic of dromeosaurids and has been observed in Deinonychus , Dromaeosaurus , and Saurornitholestes ( Currie et al. 1990; Currie 1995). This character has also been observed in some larger theropods like carcharodontosaurids, megalosaurids and neovenatorids ( Brusatte et al. 2008, 2012; Benson 2010). Characteristics of these teeth are similar to those of the dromaeosaur Pyroraptor olympius (Allain and Taquet 2002) in the density of denticles (6 posterior denticles/mm) and the square denticle morphology, so the probability is high that our sample could belong to the same taxon.

Discussion.—Statistically, the teeth from the Pyrenean sample grouped together with Pyroraptor teeth in the three discriminant analyses performed ( SOM: Table 2).

Therefore, considering the characters that identify our sample as a dromaeosaurid, the similarity of morphological and numerical data to those of Pyroraptor teeth and the correct assignation by the discriminant analyses of our sample to Pyroraptor , these teeth are best identified as? Pyroraptor olympius .