The rise of macropredatory pliosaurids near the Early-Middle Jurassic transition

The emergence of gigantic pliosaurid plesiosaurs reshaped the trophic structure of Mesozoic marine ecosystems, and established an  ~ 80 million-year (Ma) dynasty of macropredatory marine reptiles. However, the timescale of their ‘defining’ trait evolution is incompletely understood because the fossil record of gigantic pliosaurids is scarce prior to the late-Middle Jurassic (Callovian),  ~ 165.3 Ma. Here, we pinpoint the appearance of large body size and robust dentitions to early-Middle Jurassic (Bajocian) pliosaurids from northeastern France and Switzerland. These specimens include a new genus that sheds light on the nascent diversification of macropredatory pliosaurids occurring shortly after the Early-Middle Jurassic transition, around  ~ 171 Ma. Furthermore, our multivariate assessment of dental character states shows that the first gigantic pliosaurids occupied different morphospace from coeval large-bodied rhomaleosaurid plesiosaurs, which were dominant in the Early Jurassic but declined during the mid-Jurassic, possibly facilitating the radiation and subsequent ecomorph acme of pliosaurids. Finally, we posit that while the emergence of macropredatory pliosaurids was apparently coordinated with regional faunal turnover in the epeiric basins of Europe, it paralleled a globally protracted extinction of other higher trophic-level marine reptiles that was not completed until after the earliest-Late Jurassic,  ~ 161.5 Ma.

'Simolestes' keileni and PIMUZ A/III0521 have thus been advocated as "evidence for the continuous presence of gigantic apex predatory plesiosaurs in Europe" following a marine reptile turnover in western Europe (Fischer et al. 22 , p. 28) that spanned the Aalenian (earliest-Middle Jurassic), and was marked, among others, by the replacement of Early Jurassic large-bodied rhomaleosaurid (Rhomaleosauridae) plesiosaurs by archetypal later Jurassic pliosaurids that then dispersed globally as the highest trophic-level predators 22 .Notably, though, no unambiguous pliosaurid fossils were actually identified from these studied successions, and the systematic affinities of 'S' .keileni and PIMUZ A/III0521 have hitherto remained uncertain.
We provide detailed osteological description of 'S' .keileni and perform phylogenetic and multivariate analyses (Electronic Supplementary Material 1-5), targeting 'S' .keileni and PIMUZ A/III0521, to: (1) establish the phylogenetic placement of the specimens within Plesiosauria; (2) compare the dental morphospace occupation of 'S' .keileni with that of pliosaurid and rhomaleosaurid plesiosaurs; and (3) explore the timescale and global context of plesiosaur apex-predator turnover associated with the Early-to-Middle Jurassic transition.

Plesiosaur dental terminology
Our terminology for the anatomical orientation of plesiosaur teeth refers to 'apical' as the direction toward the tooth crown apex, and 'basal' describing the direction towards the cervix dentis 25 .Likewise, 'distal' and 'mesial' indicate the directions either away from or towards the snout tip, respectively.Lastly, 'labial' implies the direction towards the lips, and 'lingual' implies the direction towards the tongue.Plesiosaur dental enamel surface morphology complies with other recent studies 3,5,[26][27][28][29][30][31][32] in defining 'apicobasal ridges' as extending longitudinally from the crown apex to base, and also usually being semicircular or triangular in cross-section.In turn, 'ridglets' refers to subtle apicobasally-oriented enamel structures often developed between adjacent apicobasal ridges or on the non-ridged enamel surface; 'ridglets' can also be smooth or developed into a vermiculate surface ornamentation (Madzia 32 , Fig. 7).

Phylogenetic analyses
The phylogenetic relationships of pliosaurid plesiosaurs were investigated using the dataset of Sachs et al. 33 .We obtained first-hand scores for MNHNL BU159 and PIMUZ A/III0521, and also added information for the Early Jurassic (late Pliensbachian) pliosaurids Arminisaurus schuberti 19 and Cryonectes neustriacus 18 , and for the Middle Jurassic (middle Callovian) thalassophonean Eardasaurus powelli 34 , based on original observations, photographs, and the literature.Our TNT 1.6 35,36 search methods utilised an ordered 'ccode' set, with (1) an unweighted parsimony analysis (UPWa); (2) a weighted parsimony analysis (IWa) with K = 6; (3) IWa with the K-value selected so that the weight ratio between no homoplasy and maximum possible steps was 1 to 10 (default value); and (4) enforced monophyly of MNHNL BU159 and Simolestes vorax to assess the sister-taxon relationship between the two operational taxonomic units (OTUs) as indicated by original assignment of MNHNL BU159 to Simolestes 20 .Maxtrees were manually fixed at 'hold 200000;' .Our initial 'New Technology' search involved 1000 addition sequences and default settings activated for sectorial searches, ratchet, drift, and tree fusing.A subsequent 'Traditional Search' with tree bisection-reconnection (TBR) branch-swapping was performed on trees saved to RAM.Bremer support was calculated for UPWa with TBR and sub-optimal trees retained with up to three additional steps.Node support was determined using Symmetric Resampling for IWa with a 'Traditional' search, 1000 replicates, the default change probability P = 33, and output expressed as GC frequency differences.
Tree topologies and numerical results from our phylogenetic analyses, as well as our character state matrix are presented in Electronic Supplementary Material 1 and 2.

Multivariate analyses
We added MNHNL BU159 to the pliosaurid dental character state dataset of Zverkov et al. 3 , but with a corrected carinal score (character 3) for the 'Crimean pliosaurid' GFMSU h-216 (0 → 2) 3,5,37 , and new information on selected rhomaleosaurid plesiosaurs (Electronic Supplementary Material 3).Our modified matrix (Electronic Supplementary Material 3) was subjected to a 50% completeness threshold to mitigate the effects of missing state entries.The data were also scaled to equal variance and a zero mean applied through subtraction of the mean value for each character divided by the standard deviation.Using the cluster 2.1.0package in R 38 we applied the Gower metric 39 to create a distance matrix.Our cluster dendrograms were produced using the stats package and the Ward.D2 method.Our principal coordinates analysis (PCoA) was undertaken with the ape 5.3 package 40 and a Gower metric with Cailliez correction for negative eigenvalues.All R code is supplied in the Electronic Supplementary Material 4.

Nomenclatural acts
This published work and the nomenclatural acts it contains have been registered in ZooBank, the proposed online registration system for the International Code of Zoological Nomenclature (ICZN).The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSIDs to the prefix http:// zooba nk.org/.The LSIDs are urn:lsid:zoobank.org:pub:5CF1780F-3728-423C-A1E5-111DE436F2D0for this publication and urn:lsid:zoobank.org:act:1ED4F59D-AEAB-4142-872C-2B974FFD8D05for the new genus Lorrainosaurus.

Diagnosis
Large-bodied thalassophonean pliosaurid autapomorphically distinguished by a transversely broad, 'wedgeshaped' splenial contact that extends anteriorly to the level of the fourth mandibular alveolus.Lorrainosaurus keileni also displays a unique character state combination: (1) laterally expanded and posteriorly constricted 'spatulate' symphyseal section of the mandible bearing five to six alveoli; (2) lateral trough on the mandible anterior to the glenoid fossa; (3) a retroarticular process that is shorter than the glenoid fossa; (4) retroarticular process with posteroventrally oriented dorsoventral long axis and slightly posteromedially inflected mediolateral long axis; (5) wide posteromedial seperation of the coracoids; (6) posterolateral edge of the coracoid (cornu) projecting beyond the level of the glenoid fossa (Fig. 1).

Description and comparisons of MNHNL BU159
Cranium and mandible MNHNL BU159 comprises an incomplete skeleton that was apparently disarticulated and dispersed prior to burial.The cranium was not described by Godefroit 20 , but is represented by a section of the maxilla that preserves at least four discernible alveoli, but potentially has up to six tooth positions accommodated in succession (Fig. 2).The alveoli (herein designated MA1-MA4, Electronic Supplementary Material 6, Fig. S3a) are 21-24 mm in maximum diameter and upright rather than procumbent, suggesting an original placement towards the posterior maxillary tooth row (based on comparisons with complete dentitions attributed to Pliosaurus 43 .However, MA2 is offset out of alignment, and is thus reminiscent of the transversely constricted mid-maxillary tooth row in Liopleurodon ferox (Andrews 44 , p. 6, Text-Fig.1).Indeed, the finished exterior bone surface is perforated by sparse foramina and has an undulating profile that expands laterally around the alveoli, but is constricted by a vertical trough that likely bordered a diastema between MA2-MA3.The medial and dorsal surfaces of the maxilla fragment are damaged, with the dorsal surface having suffered severe corrosion, possibly through abrasion during transport and subsequent bioerosion on the seafloor.
In contrast to the cranium, the mandible of MNHNL BU159 is largely intact with a well-preserved symphyseal section (Electronic Supplementary Material 6, Fig. S2) and exterior bone surfaces extending posterior to the retroarticular processes (Figs. 3, 4 and 5, Electronic Supplementary Material 6, Fig. S4).Godefroit ( 20 , p. 86) identified up to six alveoli in the symphyseal part of the mandible with the first and sixth being smallest and possessing a diagnostic "forme elliptique".We alternatively interpret the alveolar shape as being more irregularly oval to circular in outline, with five and a half symphyseal alveoli (designated mA1-mA6) discernible on the right mandibular ramus, and at least five on the left (Electronic Supplementary Material 6, Figs S2a, S3b).
Externally, the mandibular symphysis of MNHNL BU159 encloses an autapomorphically broad and 'wedgeshaped' splenial contact that extends anteriorly up to the level of mA4.The splenial also forms a projecting platform along the symphyseal midline that lacks any obvious contribution from the coronoid as occurs in B. lucasi, P. philarchus, P. kevani, and K. queenslandicus 48,49,51,64 ; both the coronoid and angular contact the mandibular symphysis in Pliosaurus almanzaensis 65 .Strikingly similar "wide ventral ridge[s]" have been illustrated on the mandibular symphyses of the rhomaleosaurids A. megacephalus (Smith 59 , p. 6, Fig. 3) and Macroplata tenuiceps (Ketchum & Smith 66 , p. 1072, Fig. 1), but these do not integrate the splenial as a prominent 'wedgeshaped' element.
The external surfaces of the dentary are perforated by numerous small nutrient foramina (Electronic Supplementary Material 6, Fig. S2b,c).Foffa et al. 67 showed that such foramina connect to intra-osseous channels that potentially housed a dermal sensory system.Similar interpretations have been proposed for the mandibular channels in ichthyosaurs 68 , and might evince crocodilian-like pressure receptors 69 , or electroreceptors as in some aquatic mammals (e.g.dolphins) 70 .
Most of the post-symphyseal alveolar row has been lost to weathering, although a sequence of four-five anterior alveoli (mA9-mA13) are still preserved on the right mandibular ramus (Fig. 3).The most complete of these (mA11-mA12) are 31-27 mm in maximum diameter, respectively, suggesting that the dentition was anisodont 43,71 , with the largest functional teeth situated in the rostral-most section of the jaw around tooth positions mA4-mA5.Andrews 44 reported an identical tooth-size distribution in S. vorax, and anisodont dentitions also occur in species of Pliosaurus 43 , L. ferox 63 , A. pavachoquensis 46 , Monquirasaurus boyacensis 72 and K. queenslandicus 51 .
Godefroit ( 20 , p. 80) suggested that a "profonde encoche" (= "deep notch") along the exposed post-symphyseal edge of the splenial articulated with the coronoid, although this could not be confirmed.On the other hand, www.nature.com/scientificreports/ the angular clearly extends along the entire length of the mandible and underlaps the retroarticular process; anteriorly the angular intercalates between the splenial and dentary behind the symphyseal confluence (Fig. 3).None of the proximal mandibular elements have traceable sutures, but remnants of the surangular, angular, prearticular (extending posteriorly below the glenoid as in H. tomistomimus 16 , and articular all appear to be in life-position (Fig. 5 and Electronic Supplementary Material 6, Fig. S4a).The mandibular fossae are badly damaged and the coronoid processes, together with most of the surangular and dentary have eroded away to expose the floors of the Meckelian canals (Fig. 3a).
The articular forms the posterior margin of the glenoid in MNHNL BU159, which is also situated at the level of the tooth row (Druckenmiller & Russell 74 , p. 45, character 82).The retroarticular processes (Electronic Supplementary Material 6, Fig. S4c) are posteromedially inflected with their mediolateral long axes and posteroventrally oriented with their dorsoventral long axes.The maximum anteroposterior length (115 mm) is equivalent to the length of the glenoid, and the straight dorsal and curving ventral margins conforming to the "Type III" category listed as diagnostic for P. brachydeirus and P. macromerus by Knutsen ( 52 , p. 266, Fig. 6).
As noted by Godefroit 20 , the dental enamel of MNHNL BU159 is densely ornamented by 55 apicobasal ridges that circumscribe the crown base; only 24 enamel ridges extend to the tooth apex with at least eight terminating prior to the worn tip.Some short enamel ridglets are also interspersed between the apicobasal ridges.The enamel ridge cross-sections are sub-triangular, with one branching ridge present on the lingual surface (Godefroit 20 , p. 81).Branching enamel ridges are absent in S. vorax 3 but occur elsewhere in P. dawni 63 , B. lucasi 48 , M. eulerti 5 , 'P.' hudsoni (D.M. pers.obs.), and various isolated pliosaurid teeth 30 including the specimen identified as the 'Maryevka pliosaurid' (SOIKM KP-28988) or Thalassophonea indet.'Morphotype 1' by Zverkov et al. 3 .Notably, while the MNHNL BU159 tooth crown is most compatible with the 'Maryevka pliosaurid' , it lacks development of the apicobasal ridges as "meandering" cutting edges (Zverkov et al. 3 , p. 829).

Postcranial elements
Only a handful of postcranial bones were recovered with MNHNL BU159.Godefroit 20 listed a cervical rib and some dorsal rib fragments representing the axial skeleton.The cervical rib (Fig. 6a-e) is compact with "co-joined" (Benson & Druckenmiller 1 , appendix 2, character 160) dorsal articular facets separated by a transverse groove that can be traced onto the anterior and posterior surfaces of the rib shaft.Ventrally, the shaft becomes shallowly downcurved and markedly compressed to form lobate anterior and posterior processes (59 mm in combined anteroposterior length) resembling those on the short anterior-most cervical ribs of Jurassic pliosaurids like Liopleurodon ferox (Andrews 44 , p. 15, Text-Fig.4).
The dorsal rib fragments include one reassembled section (Fig. 6g) that has a distinctly circular cross-section with "diamètre de 40 mm" (Godefroit 20 , p. 82).However, we also identified parts of at least three gastral ribs, including two rod-shaped lateral elements with circular cross-sections, and a medial element with distinctively tapered non-bifurcating ends (Fig. 6h).
The appendicular elements of MNHNL BU159 include a disc-like mesopodial that is still encased in matrix (Fig. 6i), and a phalanx (Fig. 6j-m) with constricted shaft and rounded articular ends.Proportionally, this phalanx corresponds to the "long and slender (~ 2-3 times as long proximodistally as broad anteroposteriorly)" state description of Benson  www.nature.com/scientificreports/Finally, Godefroit 20 identified a right coracoid (Fig. 7) with maximum length/width of 710/380 mm.This element is highly fractured and missing part of its medial mid-section, but preserves a "plate-like" (Benson & Druckenmiller 1 , appendix 2, character 212) anterior process projecting from the anteromedial edge of the intercoracoid contact.Laterally, the anterior process borders the concave posterior margin of the pectoral fenestra (e.g. as reconstructed in the pectoral girdle of Simolestes vorax Andrews 44 , p. 29, Text-Fig.8).The intercoracoid contact is dorsoventrally thickened and sigmoidal in visceral profile where it supports a mediolaterally directed buttress extending laterally towards the glenoid articulation on the dorsal side.This identifies the element as the left coracoid.Anteriorly and posteriorly, there is a depression adjacent to the buttress.The obverse ventral surface of the coracoid is flat but becomes shallowly concave distally.Posteromedially, the right and left coracoids would have diverged, like those of Attenborosaurus conybeari (Sollas 14 pl.23, Fig. 3) or Brachauchenius cf.lucasi (Albright et al. 48, p. 37, Fig. 10), and were more widely separated than in Peloneustes philarchus (Andrews 44 , p. 54, Text-Fig.21), Simolestes vorax (Andrews 44 , p. 29, Text-Fig.8), and Hauffiosaurus zanoni (Vincent 17 , p. 347, Fig. 5), but were not embayed as suggested by the rounded posterior extremity.By contrast, the lateral margin of the coracoid is indented by a long concavity.The adjacent glenoid articular facet is offset from the small triangular scapular facet by about 130°.The projecting posterolateral edge (cornu) is slightly wider than the glenoid and rugose, possibly for insertion of the m.coracobrachialis 20 .

Diagnostic character states of Lorrainosaurus keileni
Despite being known from a partial skeleton, the holotype of Lorrainosaurus keileni (MNHNL BU159) clearly differs from other currently documented pliosaurid taxa based on a unique combination of characters, including one autapomorphy.
Autapomorphically the splenials in L. keileni are transversely broad and 'wedge-shaped' and they extend anteriorly to the level of the fourth mandibular alveolus, thus forming a large part of the ventral mandibular symphysis.In other pliosaurids such as Simolestes vorax, Peloneustes philarchus, and Liopleurodon ferox, the splenials are either narrower and/or they do not form a large part of the ventral symphysis (see, e.g.Ketchum & Benson 64 , pl. 3, Fig. 6, Noè 63 , Figs. 42, 139).
The presence of five to six alveoli in the symphyseal part of the mandible was described for S. vorax 44 , 'Polyptychodon' hudsoni 45 , and Acostasaurus pavachoquensis 46 .Sachicasaurus vitae bears three-four tooth positions 4 whereas other pliosaurids usually have a higher number of teeth adjacent to the symphysis (see description and comparisons above).
The presence of a lateral trough anterior to the mandibular glenoid is a character that distinguishes Lorrainosaurus from all other pliosaurids except for Hauffiosaurus and P. kevani (see Benson & Druckenmiller 1 , character 121).
The retroarticular process in Lorrainosaurus is shorter than the glenoid fossa.A similar condition of a retroarticular process that is either shorter or subequal in length with the mandibular glenoid was described for a number of pliosaurids including Pliosaurus spp., L. ferox, Megacephalosaurus eulerti or B. lucasi (see Benson & Druckenmiller 1 , character 116).However, some taxa such as S. vorax (see Noè 63 , Fig. 125), Arminisaurus schuberti 19 , Cryonectes neustriacus 18 , Hauffiosaurus spp. 16or A. pavachoquensis 46 have a retroarticular process that is longer than the glenoid fossa.
The retroarticular process in Lorrainosaurus has also a dorsoventral long axis that is posteroventrally inclined and a transverse long axis that is slightly posteromedially inflected.Such morphology also occurs in Rhaeticosaurus mertensi 83 , A. schuberti 19 , Kronosaurus queenslandicus 51 , S. vitae 4 , and A. pavachoquensis 46 , but is absent in other pliosaurids (see Benson & Druckenmiller 1 , characters 122 and 123).
Finally, the posteromedial side of the coracoid of L. keileni is strongly divergent and curves laterally.A similar condition is present in the pliosaurids Attenborosaurus conybeari 14 and Brachauchenius cf.lucasi 48 , whereas in other pliosaurids such as S. vorax, Hauffiosaurus zanoni, and Luskhan itilensis the posterior portions of the coracoids are only slightly split 6,17,44 (Electronic Supplementary Material 6, Fig. S5).

Phylogenetic relationships
Although the tree topology resulting from UPWa is unresolved (Fig. 8a), the majority-rule consensus tree and IWa trees find topologies broadly congruent with those inferred through other recent studies assessing the phylogenetic relationships of pliosaurid plesiosaurs (e.g. 6,11,34,84), and reconstruct L. keileni and PIMUZ A/III0521 within Thalassophonea, as earliest-diverging members of Brachaucheninae.Owing to the insufficient completeness of L. keileni and PIMUZ A/III0521, such placement needs to be treated with caution.Rather, it should only be considered to support the thalassophonean origin for the grouping.
Lorrainosaurus keileni + PIMUZ A/III0521 are returned as sister taxa in a subset of trees using an IWa with K = 6, based on their posteroventrally inflected dorsoventral orientation of the long axis of the retroarticular process (122:0 → 1).Alternatively, L. keileni + PIMUZ A/III0521 are united by the possession of a medially bowed mandible anterior to the glenoid (111: 1 → 0), and a prominent longitudinal trough incising the lateral surface of the mandible anterior to the glenoid (121:0 → 1) under IWa settings with K = 28.641590(63 steps of homoplasy downweighted 10 times).Lorrainosaurus keileni + PIMUZ A/III0521 additionally share a posteromedially inflected mediolateral orientation of the long axis of the retroarticular process (123:0 → 1) with brachauchenines.

Discussion and conclusions
At 1.33 m and ~ 1.5 m in maximum length, the mandibles of Lorrainosaurus keileni and PIMUZ A/III0521, respectively, proportionately exceed that of Simolestes vorax at 970 mm 44 and approach the mandibular lengths of later-diverging thalassophonean taxa, such as the Cretaceous brachauchenines Brachauchenius lucasi at 1.25 m 48 or Megacephalosaurus eulerti at 1.71 m 50 .This suggests that large skulls appeared early in their evolutionary history (at least by the early Bajocian 21 , after ~ 171 Ma).By contrast, mandibular lengths of even the largest rhomaleosaurids are less spectacular, with the Early Jurassic Rhomaleosaurus zetlandicus at 695 mm 86 , Atychodracon megacephalus at 830 mm 59 , the Middle Jurassic Borealonectes russelli at up to 512 mm 87 , and Maresaurus coccai at a maximum of ~ 1.1 m 21 .Presumably, such variation not only reflected smaller skull sizes but also different feeding styles and ecologies.Certainly, while the jaws of gigantic pliosaurids were seemingly capable of massive adductive forces, their characteristically elongate and structurally 'weak' skull shape was hydrodynamically optimised for fast crushing bites 88 .Rhomaleosaurids, in turn, had broader heads and apparently employed vigorous shake and twist feeding to dismember prey 89 .These interpretations are consistent with their dental morphologies, which as we show, diverged from curved and pointed teeth in rhomaleosaurids, possibly adapted for feeding on fish and cephalopods 90 , to robust conical teeth in early thalassophoneans, like L. keileni that may have fed on fleshy prey including larger fish and aquatic tetrapods 3,90 .Interestingly, our results further suggest that some pliosaurids dentally converged on rhomaleosaurids concurrent with their decline across the later-Middle Jurassic (Callovian, up to ~ 161.5 Ma) 91 , while others specialised towards trihedral cutting teeth 3 by the Late Jurassic (before the Kimmeridgian, ~ 154.8 Ma).Lastly, the archetypal conical-toothed morphology typified by L. keileni subsequently dominated in later-Early Cretaceous thalassophoneans (from the Aptian, ~ 121.4 Ma) 3 .
The incipient radiation of macropredatory pliosaurids has been associated with a landmark turnover of Earlyto-Middle Jurassic marine reptile assemblages inhabiting the northwestern Tethyan epicontinental periphery of what is today western Europe 22 .Notably, this coincides with abrupt oceanic cooling over the earliest Middle Jurassic interval (Aalenian, ~ 174.7 Ma) 92 , and accompanying extinctions affecting nektonic invertebrates, in particular cephalopods 93,94 .The ensuing recovery of major belemnite (Belemnopseina) 93 and ammonite (Ammonitina) 94 groups was distinguished by biogeographical provincialism, involving separation into distinct Tethyan and Boreal faunas 93,95 .
The adaptive diversification of thalassophoneans as apex-predators might have facilitated via local food chain disruptions triggering ecological niche vacation by rhomaleosaurids and other larger-bodied marine reptiles in the northwestern Tethys 22,96 .However, the consequent innovation and global dispersal of macropredatory pliosaurids patently did not accelerate until the early-Late Jurassic (Oxfordian, by ~ 154.8 Ma) 97 , and was approximately concurrent with the final extinction of rhomaleosaurids (potentially induced by climatic warming across In summary, our results demonstrate that thalassophonean pliosaurids were the geologically longest-ranging clade of macropredatory marine tetrapods with a fossil record spanning ~ 80 Ma.Their advent paralleled a regional marine faunal turnover in the earliest Middle Jurassic 22,93,94 that was perhaps associated with rapid oceanic temperature changes and the progressive decline of coeval macrophagous marine reptiles specialised for feeding on cephalopods 97 .These included coeval large-bodied rhomaleosaurids 90 , which persisted until the latest Middle Jurassic 91 but were likely not direct competitors.Rather, rhomalosaurids were ecomorphologically partitioned from the earliest thalassophoneans, which otherwise pioneered plesiosaur macropredator niches to dominate the Mesozoic seas.

Figure 1 .
Figure 1.Skeletal remains of the holotype (MNHNL BU159) of Lorrainosaurus keileni.(a) Reconstruction in lateral view showing recovered elements.(b) Tooth crown with root.(c) Posterior section of mandible in lateral view.(d) Glenoid section of mandible in articular view.(e) Complete mandible in ventral view.(f) Enlargement of the mandibular symphysis.(g) Coracoid in dorsal view.