Theropoda

Malafaia, Elisabete, Mocho, Pedro, Escaso, Fernando, Narvaéz, Ivan & Ortega, Francisco, 2024, Taxonomic and stratigraphic update of the material historically attributed to Megalosaurus from Portugal, Acta Palaeontologica Polonica 69 (2), pp. 127-171 : 147-151

Theropoda Marsh, 1881

Theropoda indet.

SOM 5: fig. S2.

Previous identifications: Most of the tooth crown fragments are labeled as Megalosaurus insignis and some of them were mentioned by Sauvage (1897 –1898), Lapparent and Zbyszewski (1957), and Mateus (2005), although none of these authors figured them. The only exceptions are: (i) a specimen collected in the region of Pombal (MG 8778; SOM 5: fig. S2A 1 –A 4), which is part of the material used for the description of Megalosaurus pombali ( Lapparent and Zbyszewski 1957: 25; pl. 28: 105) and (ii) the tooth fragment from Viso (MG 73; SOM 5: fig. S2E 1 –E 5) that is part of a set of three tooth fragments described by Sauvage (1897 –1898: 40, pl. 8: 16) as belonging to Megalosaurus sp. Later, Lapparent and Zbyszewski (1957: 27, pl. 12: 4, 5, 20) attributed these three specimens (including MG 73) as belonging to Megalosaurus cf. pannoniensis . The ungual phalanges (MNHN/UL.EPt.025a and b) were figured by Lapparent and Zbyszewski (1957: 23, pl. 12: 18, 22) and attributed to Megalosaurus sp.

Material. —Several fragments of tooth crowns (MG 14, 4812, 4815, 4816, 8776, 8778; SOM 5: fig. S2A 1 –A 4; MG 25199, MNHN/UL.EPt.022, SOM 5: fig. S2B 1 –B 6; MG 73, SOM 5: fig. S2E 1 –E 5) and two small ungual phalanges (MNHN/ UL.EPt.025, SOM 5: fig. S2C 1 –C 4, D 1 –D 4). The label associated to MG 4812 indicates that this specimen comes from the “Lusitanian” of Ourém ( Portugal) ( Fig. 4 ) and was probably collected from Kimmeridgian levels of the Alcobaça Formation ( Fürsich et al. 2021). The tooth fragments (MG 4815) were collected at Murteiras, in the municipality of Foz do Arelho ( Portugal), from sedimentary rocks of the Tithonian Bombarral Formation ( Fig. 3 ) ( Manuppella et al. 1999a). The tooth fragments (MG 14) are labeled as coming from a locality southwest of Vermoil, in the municipality of Pombal ( Portugal). The sedimentary levels around this locality correspond mainly to Lower Cretaceous deposits ( Fig. 5 ), but a large section of the “Complexo de vale de Lagares” crops out southeast to Vermoil ( Teixeira et al. 1968). These levels have been recently included in the Alcobaça Formation ( Fürsich et al. 2021). It is probable that the tooth fragments were collected from these Kimmeridgian levels of the Alcobaça Formation. Other tooth fragments (MG 4816, 8778, 25199) are labeled as coming from Pombal ( Portugal), but more precise geographic information is not available for these specimens. MG 8776 was collected at Atalaia (Lourinhã, Portugal), from Kimmeridgian–Tithonian deposits of the Sobral Formation ( Fig. 2 ). A tooth crown (MNHN/UL.EPt.022) and the ungual phalanges (MNHN/UL.EPt.025) came from Porto Dinheiro (Lourinhã, Portugal) and were probably collected in upper Kimmeridgian–lowermost Tithonian levels of the Praia da Amoreira-Porto Novo Formation ( Fig. 2 ) ( Manuppella et al. 1999a). Finally, MG 73 was collected at the locality of Viso, in the region of Montemor-o-Velho (Coimbra, Portugal). This specimen came from a fossil site found at km 20 of the railway ( Sauvage 1897 –1998), where a predominantly sandstone sequence of the “Sandstones and Mudstones of Viso” ( Barbosa et al. 2008) crops out ( Fig. 7 ). The study of the palynological record in some areas within this unit (here referred to as “Viso Formation”) indicates an age ranging from the Santonian to the Campanian with possible extension into the early Maastrichtian ( Barbosa et al. 2008).

Description.—With the exception of one specimen (MNHN/ UL.EPt.22), which is an almost complete tooth crown (SOM 5: fig. S2B 1 –B 6), all the other specimens are particularly incomplete and distorted. MNHN/UL.EPt.22 is covered by a layer of sediment obscuring most of the denticles and the enamel ornamentation, preventing them to be described. This specimen corresponds to a relatively large (AL = 22.55), elongated (CHR = 2.32) and moderately compressed (CBR = 0.64) crown. It is triangular in lateral view and slightly recurved distally with the mesial margin strongly convex, but the distal margin is mostly straight. The distal carina is visible in a small part of the central sector of the distal margin and bears a large number of small denticles (21 denticles per 5 mm). The latter are rectangular (slightly longer mesiodistally than wide apicobasally), extend perpendicular to the carina, and with a symmetrically convex external margin (SOM 5: fig. S2B 5). The tooth fragment from Viso (MG 73) is represented by a relatively well-preserved tooth crown without the apex (SOM 5: fig. S2E 1 –E 5). Despite the absence of the latter, the preserved fragment suggests that it would be relatively elongated relative to the basal mesiodistal length. The crown is labiolingually compressed (CBR = 0.5), with a lanceolate basal section. The distal carina has poorly preserved denticles extending to the cervix and the mesial carina, which seems to have also denticles, but it is incomplete, and their extension cannot be determined. The distal carina is centrally placed on the distal surface. Interdenticular sulci, marginal and transverse undulations are not visible in the preserved fragment of the crown. Both labial and lingual surfaces are slightly convex. The enamel is mostly smooth or has a very subtle irregular ornamentation.

The ungual phalanges (MNHN/UL.EPt.025a and b) are slightly recurved ventrally and have well-developed lateral grooves, which are mostly symmetrical and extend along the entire length (SOM 5: fig. S2C 1 –C 4, D 1 –D 4). The proximal end of both phalanges is missing, which makes it difficult to determine their anatomical position and to discuss their taxonomy in more detail. MNHN/UL.EPt.025a (SOM 5: fig. S2C 1 –C 4) has a triangular section, with a rounded dorsal surface and a mostly flat ventral margin whereas the other ungual, MNHN/UL.EPt.025b (SOM 5: fig. S2D 1 –D 4) is much narrower mediolaterally with a blade-like section.

Remarks.—Most of the tooth crown fragments are incomplete, but several of them show evidence of denticles and can therefore be attributed to indeterminate theropods. MNHN/UL.EPt.22 is a relatively large denticulated ziphodont teeth with mesial carina that appears to terminate above the cervix. These features together with the currently known record of Late Jurassic theropods from the Lusitanian Basin indicate that this specimen likely belong to an indeterminate averostran theropod. However, we have not been able to find any other feature that would allow a more precise identification. The reclassification rate of the performed discriminant analysis is 70.91% and the average of cases correctly classified is 60% for non-abelisauroid Ceratosauria ( Genyodectes , 78%; Ceratosaurus , 41%), 62% for Abelisauroidea ( Abelisaurus , 60%; Indosuchus , 50%; Majungasaurus , 75%), 92% for Megalosauroidea ( Marshosaurus , 100%; Torvosaurus , 84%), 53% for Allosauroidea ( Sinraptor , 73%; Allosaurus , 55%; Acrocanthosaurus , 69%; Carcharodontosaurus , 47%; Giganotosaurus , 71%; Mapusaurus , 43%), 71% for Tyrannosauroidea ( Guanlong , 83%; Raptorex , 71%; Alioramus , 100%; Gorgosaurus , 42%; Daspletosaurus , 58%; Albertosaurus , 54%; Tyrannosaurus , 91%), and 65% for Dromaeosauridae ( Deinonychus , 75%; Dromaeosaurus , 55%). Result of this analysis classifies the tooth crown fragment MG 73 as belonging to Gorgosaurus (see Table 1) and in the plot with the distribution of the different theropods it falls in the intersection of the morphospace of several large sized taxa, including Acrocanthosaurus , Torvosaurus , and Indosuchus ( Fig. 16 ). This specimen is a medium size (estimated CH around 25 mm), ziphodont tooth, with an oval basal section and poorly preserved mesial and distal denticles in both mesial and distal surfaces.

The fossil record of continental vertebrates known from the Upper Cretaceous of the Lusitanian Basin is scarce and currently restricted to three areas in the northern sector of the basin: the region of Aveiro and Viso, in the Aveiro sub-basin, and Taveiro, in the Figueira da Foz sub-basin. Theropod dinosaurs are represented, beside the specimens first described by Sauvage (1897 –1898) and Lapparent and Zbyszewski (1957), by a collection of mostly small-sized isolated teeth, some caudal vertebrae (first interpreted as belonging to pterosaurs) and few ungual phalanges interpreted as belonging to different coelurosaurian groups ( Antunes and Sigogneau-Russell 1991, 1992; Galton 1994, 1996; Antunes and Mateus 2003). However, there are also some larger tooth crown fragments that have been attributed to “ Megalosauridae ” (e.g., Antunes and Sigogneau-Russell 1991; Galton 1996). This material is part of a collection provisionally deposited in the Centro de Estudos Geológicos of the Universidade Nova de Lisboa ( Antunes and Mateus 2003), but unfortunately, we were unable to have yet access to it. Due to the poor preservation of MG 73, a more precise taxonomic identification is not possible, and it is therefore attributed here to a medium or large-sized indeterminate theropod taxon.

The ungual phalanges belong to very small individuals, but their taxonomic discussion is difficult. They have a relatively strong ventral curvature and a triangular cross-section, which together with the presence of well-developed and mostly symmetrically placed lateral grooves suggest that these ungual phalanges probably belong to a pedal digit of an indeterminate theropod. However, their attribution to a more inclusive clade is not possible mostly because the proximal end is missing in both phalanges.

Ceratosauria Marsh, 1884

Genus Ceratosaurus Marsh, 1884

Type species: Ceratosaurus nasicornis Marsh, 1884 , from the late Kimmeridgian –early Tithonian Brushy Basin member of the Morrison Formation in Garden Park, Colorado, USA .

cf. Ceratosaurus sp. Marsh, 1884

Fig. 17 .

Previous identifications: MG 8777 is associated with a label that says Megalosaurus pombali, Ribamar , but was described by Lapparent and Zbyszewski (1957) as coming from Atalaia and it was assigned to Megalosaurus insignis ( Lapparent and Zbyszewski 1957: 22, pl. 12: 9). The tooth crown fragment MNHN/UL.Ept.021 is associated with a label with the identification M. insignis and possibly corresponds to the specimen from Porto das Barcas mentioned by Lapparent and Zbyszewski (1957: 22) as belonging to this species.

Material. — Two tooth crowns (MG 8777, Fig. 17A ; MNHN/ UL.EPt.021, Fig. 17B ). MG 8777 was found in Atalaia and MNHN/UL. Ept. 021 came from Porto das Barcas. Both localities belonging to the municipality of Lourinhã ( Portugal) and the two specimens were probably collected from upper Kimmeridgian–lower Tithonian sediments of the Sobral Formation ( Fig. 2 ) ( Manuppella et al. 1999a) .

Description.—MG 8777 is represented by a relatively well-preserved tooth crown and preserves a small fragment of the root ( Fig. 17A ). The crown is quite elongated ( CHR = 2.8) and strongly labiolingually compressed ( CBR = 0.5), with a lanceolate basal section. The crown is slightly recurved distally in lateral view. The mesial margin is strongly convex whereas the distal one is slightly concave, and the apex is positioned distal to the distal end of the mesial surface. The labial surface is slightly convex, whereas the lingual surface is mostly flat. Subtle transverse undulations are visible on the lingual surface. The enamel has a faint ornamentation consisting of a series of poorly marked ridges and grooves mostly apicobasally oriented (braided texture sensu Hendrickx et al. 2015a). There is a shallow longitudinal concave surface adjacent to the distal carina on the lingual surface. A short irregular surface of the enamel (spalled surface sensu Hendrickx et al. 2015a) is present in the apical end of the crown and extends slightly into the labial and lingual surfaces. The presence of these enamel flaking in theropod teeth have been interpreted as resulting from forces produced during contact between the crown and food ( Schubert and Ungar 2005; Hendrickx et al. 2015a). Both the mesial and distal carinae are denticulated. They are mostly straight and centrally positioned in the mesial and distal surfaces, respectively. In the distal carina the denticles extend to the cervix, but in the mesial carina they end at about two thirds of the height of the crown from the tip. There are 19 and 18 denticles per 5 mm in the central and basal sectors of the mesial carina, respectively. In the distal carina there are 15 denticles per 5 mm in the apical and central sectors and 19 denticles per 5 mm in the denticulated basal sector (see SOM 2). The mesial denticles are subquadrangular, slightly apically inclined, and with convex distal margins. The mesial carina is poorly preserved apically so the number and morphology of the denticles in this part cannot be known but the central denticles are relatively well-preserved. The denticles become much smaller mesiodistally to the basal end of the denticulated carina. The distal denticles are rectangular, longer mesiodistally than apicobasally, with convex distal margins, and project perpendicularly to the carina. They become much narrower apicobasally to the crown base and mesiodistally shorter apically, ending slightly below the apex. Between the distal denticles, there are well-defined interdenticular sulci projecting towards the base of the crown. The interdenticular sulci are visible on both lingual and labial surfaces, being more evident in the central and basal sectors of the carina.

MNHN/UL.Ept.021 is represented by a small fragment of the basal part of a tooth crown ( Fig. 17B ). Although being very incomplete, the preserved fragment (preserved CH = 19.56mm; estimated CH = 35.66 mm) indicates that this specimen belongs to a relatively large sized taxon (see SOM 2). The crown is highly compressed labiolingually ( CBR = 0.53) and has a lanceolate basal cross section with a strongly convex labial surface and a flat lingual surface. The lingual surface is slightly concave longitudinally adjacent to the distal carina. The distal carina has denticles extending to the cervix, but denticles are absent in the basal sector of the mesial one carina (a small section of denticles is visible about 13 mm above the cervix). There are 12 denticles per 5 millimeters in the basal part of the distal carina. The distal denticles are rectangular, much higher mesiodistally than apicobasally and have strongly convex external margins ( Fig. 17B 6 ). They are separated by relatively large interdenticular spaces, which project into the lateral surface of the crown and delimit well-developed and obliquely oriented caudae projecting from the base of the denticles. A few short marginal undulations are visible on the lingual surface adjacent to the distal carina. As in the previously described specimen, the enamel has a subtle braided texture, which is more visible in the lingual surface adjacent to the distal carina.

Remarks.—The discriminant analysis assigned MG 8777 as belonging to Marshosaurus and MNHN/UL.Ept.021 to Genyodectes (see Table 1). In the plot, there is a large overlap of the morphospaces occupied by several taxa of medium and large-sized theropods with ziphodont dentition. Both specimens fall outside the morphospace of all defined groups but closer to those occupied by tyrannosaurids, but MG 8777 is also close to the mosphospaces of Allosaurus and Genyodectes ( Fig. 16 ). The cladistic analysis of the dentition-based data matrix with constraints and including all studied morphotypes found 30 Most Parsimonious Trees (MPTs) (CI = 0.201, RI = 0.456, L = 1332). The strict consensus tree from this MPTs (CI = 0.194, RI = 0.432, L = 1379; Fig. 18 ) is relatively well-resolved, except for one branch comprising megalosaurid and spinosaurid taxa that are mostly placed in a large polytomy. In this analysis the specimens MG 8777 and MNHN/UL.Ept.021 (Morphotype) are placed in this polytomy as the sister taxon of Piatnitzkysaurus ( Fig. 18A ). The results of the analysis pruning a priory all the morphotypes from the Lusitanian Basin but Morphotype 1 found 1 MPT (CI = 0.203, RI = 0.462, L = 1320). The Megalosauroidea clade is well resolved, but the placement of Morphotype 1 is similar to that obtained in the analysis with all morphotypes, being placed within the megalosauroid clade as the sister taxon of Piatnitzkysaurus Fig. 18B ). The crowns of the two specimens (MG 8777 and MNHN/UL.Ept.021) are strongly labiolingually compressed ( CBR = 0.53), a common dental feature of the lateral teeth in several theropods, including Ceratosaurus , Abelisaurus , Majungasaurus , Marshosaurus , and Torvosaurus ( Hendrickx et al. 2020b) . Some non-abelisauroid ceratosaurians, such as Ceratosaurus and Genyodectes , usually have blade-shaped lateral crowns with CBR lower than 0.5, but some teeth may have higher ratios ( Rauhut 2004; Hendrickx et al. 2015b, 2020b). The crown of MG 8777 is strongly elongated ( CHR = 2.35), which is higher than the mean ratio for most theropod lateral tooth crowns, except those of Genyodectes , Torvosaurus , Acrocanthosaurus , and Giganotosaurus ( Hendrickx et al. 2015b, 2020b). Both mesial and distal carinae have a high number of small denticles with a DSDI ratio near 1.2 (in MG 8777), meaning that the number of denticles in the central sector of the mesial carina is slightly higher than the number of denticles in the central sector of the distal carina. This ratio is usually less than or equal to 1 in the lateral teeth of most theropod taxa, except for Ceratosaurus , in which in some lateral teeth this ratio is higher than 1.2 ( Hendrickx et al. 2020b). As in some lateral teeth of Ceratosaurus , both MG 8777 and MNHN/UL.ePt.021 have a flattened lingual margin and a longitudinal concave surface adjacent to the distal carina in the lingual surface. The presence of a concave area adjacent to the mesial and distal carinae has been proposed as representing a neoceratosaurian synapomorphy as this feature is shared by Ceratosaurus , Genyodectes , and at least some abelisaurids ( Rauhut 2004). Morphotype 1 shows some differences relative to the dentition of Ceratosaurus , including the extension of the mesial carina, which usually reaches the cervix or very close to it ( Hendrickx et al. 2015b; Malafaia et al. 2017a). However, in some ceratosaurian taxa, such as Genyodectes , similarly to the condition in both MG 8777 and MNHN/UL.EPt.021, the mesial carina of at least some lateral tooth crowns is restricted to the apical half Rauhut 2004; Christophe Hendrickx, personal communication 2023). Despite these differences and the results of the cladistic analyses, the specimens grouped in Morphotype 1 are here tentatively assigned to Ceratosaurus based on the presence of a concave surface adjacent to the distal carina a possible synapomorphy for Ceratosauria), the symmetrical shape of the crow (with both mesial and distal carinae positioned centrally), the strongly labiolingual compression of the crown, and the relatively high number of denticles.

Figures

Fig. 4. Geological and stratigraphical context of fossil sites in the Mamede sub-basin. A. Geological map of the region of Batalha and Ourém with localities yielding fossil remains studied in this work (modified from Teixeira et al. 1968; Manuppella et al. 2000). B. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). C. Simplified stratigraphy of the Upper Jurassic sequences in the Mamede sub-basin based on Kullberg et al. (2013) and Fürsich et al. (2021).Abbreviations: Chron., Chronostratigraphy; Fm., Formation; mb., member; l ., lower; m., middle; sb., sub-basin; u., upper.

Fig. 3. Geological and stratigraphical context of fossil sites in the northern part of the Consolação sub-basin and in the Bombarral sub-basin.A. Geological map of the region between Caldas da Rainha and Alcobaça with localities yielding fossil remains studied in this work (modified from Zbyszewski and Moitinho de Almeida 1960; Camarate França and Zbyszewski 1963). B. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). C. Simplified stratigraphy of the Upper Jurassic and Lower Cretaceous sequences in the Consolação-S. Martinho, Torres Vedras and Lourinhã coastal regions. The stratigraphy for Torres Vedras and Lourinhã based on Hill (1988) and Manuppella et al. (1999a) and for the littoral of Consolação-S. Martinho do Porto based on Manuppella et al. (1999a) andAzerêdo et al. (2010).Abbreviations: Chron., Chronostratigraphy; Fm., Formation; mb., member; l., lower; m., middle; Oxfor., Oxfordian; sb., sub-basin; u., upper.

Fig. 5. Geological and stratigraphical context of fossil sites in the Mamede sub-basin. A. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). B. Geological map map of the region of Pombal and Leiria with localities yielding fossil remains studied in this work (modified from Teixeira et al. 1968; Manuppella et al. 1978). C. Simplified stratigraphy of the Upper Jurassic sequences in the Mamede sub-basin based on Kullberg et al. (2013) and Fürsich et al. (2021). Abbreviations: Berrias., Berriasian; Chron., Chronostratigraphy; Fm., Formation; mb., member; l., lower; m., middle; Oxf., Oxfordian; sb., sub-basin; u., upper.

Fig.2. Geological and stratigraphical context of fossil sites in the Consolação and Bombarral sub-basins, Portugal. A. Geological map of coastal region of Lourinhã and Peniche with localities yielding fossil remains studied in this work (modified from Camarate França et al. 1960; Manuppella et al. 1999a). B. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). C. Simplified stratigraphy of the Upper Jurassic and Lower Cretaceous sequences in the Torres Vedras and Lourinhã costal region and Consolação-S.Martinho do Porto coastal region based on Hill (1988), Manuppella et al. (1999a) and Azerêdo et al. (2010).Abbreviations:Assen., Assenta; Chron., Chronostratigraphy; Fm., Formation; mb., member; l., lower; m., middle; Oxfor., Oxfordian; sb., sub-basin; u., upper.

Fig. 7. Geological and stratigraphical context of the Figeira de Foz and Aveiro region. A. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). B. Geological map of Figueira da Foz and Aveiro region (Aveiro sub-basin) with localities yielding fossil remains studied in this work (modified from Rocha et al. 1981 and Barbosa et al. 2008). C. Simplified stratigraphy of the Upper Cretaceous sequences in the Figueira da Foz and Aveiro sub-basins based on Barbosa et al. (2008).Abbreviations: Chron., Chronostratigraphy; Fm., Formation; mb., member; l., lower; m., middle; sb., sub-basin; u., upper.

Fig. 16. Graphical results of the Linear Discriminant Analysis (LDA) of 581 tooth crowns belonging to twenty-two theropod taxa and the isolated specimens from the Lusitanian Basin studied in this work. Eigenvalue of axis 1 = 8.2989 (which accounts for 67.28% of the total variation) and eigenvalue of axis 2 = 1.129 (which accounts for 9.152% of the total variation). AL, apical length; CBW, crown base width; CH, crown height; DA, distoapical denticle density; DB, distobasal denticle density; DC, distocentral denticle density; MA, mesioapical denticle density; MB, mesiobasal denticle density; MC, mesiocentral denticle density; MCL, mid-crown length; MCW, mid-crown width; MDE, mesiobasal denticles extent.

Fig. 17. Tooth crowns attributed to cf. Ceratosaurus sp. from the Kimmeridgian–Tithonian Sobral Formation, Atalaia and Porto das Barcas (Lourinhã region, Portugal). A. MG 8777. B. MNHN/UL.EPt.021. Labial (A1, B1), distal (A2, B2), mesial (A3, B3), and lingual (A4, B4) views; basal cross-section A5, A6, B5); detail of the distal denticles (B6).

Fig. 6. Geological and stratigraphical context of fossil sites in the Setúbal sub-basin. A. Map of the Lusitanian Basin with the main structural elements and the different sub-basins (sensu Fürsich et al. 2021). B. Geological map of the Sesimbra to Cabo Espichel region with localities yielding fossil remains studied in this work (modified from Manuppella et al. 1999b). C. Simplified stratigraphy of the Lower Cretaceous sequences in the Setúbal sub-basin based on Manuppella et al. (1999b). The stratigraphic position of the Papo Seco Formation from which the studied fossils were collected is marked in green. Abbreviations: Chron., Chronostratigraphy; Fm., Formation; mb., member; l., lower; m., middle; sb., sub-basin; u., upper.

Fig. 18. Strict consensus trees resulting from a cladistic analysis performed on a dentition-based data matrix and forcing the constrains defined by Hendrickx et al. (2020a) with the five tooth morphotypes from the Lusitanian Basin (A), simplified strict consensus tree resulting from the cladistic analysis pruning a priori all morphotypes from the Lusitanian Basin but Morphotype 1 (B), and simplified strict consensus tree resulting from the analysis pruning a priori all morphotypes from the Lusitanian Basin but MNHN/UL.EPt.023 (C).