Dromaeosauridae Matthew and Brown, 1922
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publication ID |
https://doi.org/ 10.4202/app.2008.0007 |
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persistent identifier |
https://treatment.plazi.org/id/354487B5-A81D-FFB9-FFD4-578B0E0AFA43 |
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treatment provided by |
Felipe |
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scientific name |
Dromaeosauridae Matthew and Brown, 1922 |
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Dromaeosauridae Matthew and Brown, 1922
gen. et sp. indet.
Description
No significant portion of the root is preserved in any of the specimens and there are no visible signs of resorption, which, together with tooth tip− and denticle−wear, indicates that all specimens represent shed teeth. Whether shedding occurred pre− or post−mortem cannot be determined. Except for DFMMh/FV 658 and DFMMh/FV 707.1 ( Fig. 4C, E View Fig ), the specimens described here are small ( CH <10 mm). The height of the crowns (from the apex to the base of the crown) ranges from 2.81 to 24.5 mm, with a CBL ranging from 1.87 to 8.8 mm. All specimens are strongly labiolingually compressed (average CBR <0.5) and strongly distally recurved, so that the tooth apex extends behind the level of the base of the crown, except for DFMMh/FV 382 ( Fig. 4D View Fig ) and DFMMh/FV 790.5, which are less strongly recurved and less labiolingually compressed. Denticles are present on the entire distal carina of all specimens. Mesially, the serration does not reach beyond the apical half of the carina in any specimens except for DFMMh/FV 658 in which the apical 70% of the mesial carina is serrated. The cross sectional shape of all specimens is a flat oval with the exception of DFMMh/FV 790.5 where it is oval. The carinae run gradually along the midline of the teeth in most specimens except for DFMMh/FV 382, where the mesial carina is offset about 5° towards the lingual side relative to perpendicular at the base of the crown and the distal carina twists slightly toward the lingual side of the crown at its centre but approaches the perpendicular line again near the crown base. In all specimens the denticles on the mesial carina are smaller than those on the distal carina. The denticles on all specimens are of subrectangular shape in lateral view and slightly inclined apically. Wear on the tooth tip is present in all specimens except for DFMMh/FV 707.1 ( Fig. 4C View Fig ) in which the apical part is missing, and for DFMMh/FV 790.5. Given the very small size of the latter crown it is likely that specimen DFMMh/FV 790.5 belongs to a hatchling or juvenile. Denticle wear is visible on both the mesial and distal apical serrations of all specimens.
LUBBE ET AL.—LATE JURASSIC DROMAEOSAURID TEETH FROM GERMANY 405
Apart from DFMMh/FV 382, which shows multiple cracks in the enamel, and DFMMh/FV 707.1, in which the apical part is missing, all specimens are excellently preserved. In DFMMh/FV 707.1 the labial side of the crown the enamel and part of the dentine have broken off. The resorbtion facet of a partially erupted (about 50%) replacement tooth (apparently lost with the shedding of the crown) is visible on the labial side. The enamel on the lingual side is well preserved and shows three minor cracks, which run almost perpendicular toward the base. Their almost perpendicular orientation might indicate that they were caused by pressures exerted on the crown by the erupting replacement tooth.
The enamel is smooth in all specimens and ridges are generally lacking or very faint, nor are colour banding or wrinkles visible, which might indicate growth lines (compare Sweetman 2004).
Comparisons
We found no or only very few similarities to the teeth from Langenberg/Oker in the literature based on the following taxa: Archaeopteryx sp. ( Weigert 1995); Compsognathus longipes ( Stromer 1934) ; Juravenator starki ( Göhlich and Chiappe 2006) ; Carcharodontosauridae gen. et sp. indet. ( Veralli and Calvo 2004); Allosauridae gen. et sp. indet. ( Park et al. 2000); Theropoda gen. et sp. indet. (Perea et al. 2003).
For the following comparison of the Langenberg tooth specimens with other theropod teeth we chose publications with regard to a good availability of morphometric data, photos/drawings, detailed descriptions of the tooth specimens and a determination of the teeth to the family Dromaeosauridae and Troodontidae .
Comparisons with teeth of Dromaeosauridae .—The Langenberg teeth are similar to tooth IWCMS.2002.2 described by Sweetman (2004). However, it remains unclear whether the apical part of the mesial carina of this specimen is serrated or not and, moreover this tooth is slightly more recurved than any of the Langenberg teeth.
There is only a superficial resemblance between the Langenberg teeth and those of Microraptor zhaoianus ( Hwang et al. 2002) . Similar in general form and appearance, the Langenberg teeth are serrated on both their mesial and distal carina whereas they are not in M. zhaoianus . Those teeth are constricted between crown and root and are more strongly recurved distally than the Langenberg specimens. Moreover, the denticles of M. zhaoianus are proportionally much larger than those of the Langenberg teeth.
Teeth of Graciliraptor lujiatunensis ( Xu and Wang 2004) are similar to the Langenberg teeth because they show a size difference of denticles between mesial and distal serration but they differ in being less distally recurved and less sharply tapered apically. Moreover, the carinae of the rostral maxillary teeth of Graciliraptor lujiatunensis are smooth.
The Langenberg teeth are similar to those of Sinornithosaurus millenii described by Xu and Wu (2001) with respect to size difference of the denticles between mesial and distal serrations, subrectangular shape of denticles, strongly distally recurved crown and apically pointed crown, which is labiolingually compressed. The latter character is not mentioned by Xu and Wu (2001), but it is seen on their fig. 5B–I. The teeth of S. millenii differ from those of Langenberg quarry in having a groove anterior to the distal carina, and some of the premaxillary teeth have smooth carinae. Moreover, the Langenberg teeth are on average larger than those of S. millenii .
Dromaeosaurid teeth from the Late Cretaceous at four localities of southern France ( Buffetaut et al. 1986) resemble those from Langenberg in possessing distally recurved crowns, which are labiolingually compressed, but the Langenberg teeth are on average larger than those from France. There is also a distinct size difference of the denticles between the mesial and distal serrations in one specimen (SER 03, Buffetaut et al. 1986: fig. d) from France. The mesial carina of specimen NEV 12 ( Buffetaut et al. 1986: fig. a), VIC 17 ( Buffetaut et al. 1986: fig. b, c) and CHG 48 ( Buffetaut et al. 1986: fig. e) is smooth in contrast to the Langenberg specimens with the central and apical part of the mesial carinae being serrated. The teeth from southern France show proportionally finer serration than that of the teeth from Langenberg quarry.
A theropod tooth from the Wadi−Milk Formation, northern Sudan ( Rauhut and Werner 1995) resembles the Langenberg teeth in that it is strongly labiolingually compressed, and strongly distally recurved. There is also a distinctive size difference of denticles between mesial and distal serrations. In contrast the Wadi−Milk specimen shows denticles that are more strongly apically inclined.
Three teeth from the Kem−Kem−beds of the Tafilalt region, southern Morocco ( Amiot et al. 2004: pl. 1: 4–6) classified as velociraptorine dromaeosaurid resemble those from Langenberg in CH and CBL size range. They are similar with respect to size difference between mesial and distal serrations, subrectangular shape of denticles, being strongly distally recurved and possessing an apically pointed crown, which is labiolingually compressed. But there are some differences, in general form of the teeth from Morocco and in the distribution of the mesial serration over the carinae, from those of the Langenberg teeth. The denticles of the mesial carina are absent in specimen M−CH−009 whereas in specimens M−ZA−014 and M−JQ−012 the mesial carina is serrated over almost its entire length. The latter character is not mentioned in the text but it is seen on the figures ( Amiot et al. 2004: figs. 4 and 6, pl. 1).
Theropod teeth from Uña in Spain ( Rauhut 2002) classified as velociraptorine dromaeosaurid are almost indistinguishable from those from Langenberg. Especially one specimen ( Rauhut 2002: fig. 2G) resembles specimen DFMMh/FV 530 in all aspects, except that the size difference between mesial and distal denticles is slightly more developed in the Spanish specimen.
The detailed description of the teeth of Deinonychus antirrhopus ( Ostrom 1969) and morphometric data published by Smith et al. (2005) and Smith and Lamanna (2006) allow a thorough comparison with the Langenberg teeth. The former are similar in size and overall dimensions but the largest crown of one Langenberg tooth is still larger than the largest D. antirrhopus tooth in the standard. The values calculated for CMA for the Langenberg teeth fall within the margin of tooth crowns of D. antirrhopus in the standard, except for specimen DFMMh/FV 658, which is slightly less recurved. Similar values for CBR indicate that the D. antirrhopus teeth and those from Langenberg are about equally labiolingually compressed. The main differences between the two taxa are that D. antirrhopus teeth possess proportionally finer serrations, and the mesial carina is serrated over almost its entire length ( Ostrom 1969).
The Langenberg teeth are very similar to those of Velociraptor mongoliensis in being labiolingually compressed, distally recurved, showing a distinctive size difference between mesial and distal denticles, and a mesial carina, which is serrated only in its central and apical part. General form, size, and distribution of the mesial and distal serrations over the carinae of DFMMh/FV 530 match those of the tooth depicted in Barsbold and Osmólska (1999: fig. 2C). The detailed morphometric data given for the V. mongoliensis teeth by Smith et al. (2005) and Smith and Lamanna (2006) indicate that the main differences between the teeth lie in their size, with the Langenberg teeth being on average larger and showing proportionally higher values for CBL than those of V. mongoliensis .
The velociraptorine dromaeosaurid teeth from the coal mine of Guimarota (Late Jurassic, Portugal) depicted in Rauhut (2000: fig. 11.11) appear to be very similar to those from Langenberg. Denticle size difference, orientation, and shape match very nicely. Specimen GUI D 67 shows strong similarities to the Langenberg teeth and supports our hypothesis that the specimens from Langenberg quarry and those from Guimarota may belong to the same taxon.
Comparisons with teeth of Troodontidae .—Although specimen DFMMh/FV790.5 shows some similarity to teeth of Troodon formosus (see Holtz et al. 1998) in being of small size and in possession of coarser serration than any other teeth from Langenberg quarry of Oker; it also differs from the dentition of T. formosus in other aspects. The denticles of DFMMh/FV 790.5 show different proportions to those of T. formosus teeth and are only slightly inclined towards the crown apex if at all instead of being “apically hooked”. Moreover, specimen DFMMh/FV 790.5 lacks the constriction between crown and root that is typical of T. formosus teeth.
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