the adventure of the crocodyliforms by a paleontologist
Crocs !
Latest publications, 2019
Title
Jouve, Stéphane, Bouziane Khalloufi, and Samir Zouhri. 2019. Longirostrine Crocodylians from the Bartonian of Morocco and Paleogene Climatic and Sea Level Oscillations in the Peri-Tethys Area. Journal of Vertebrate Paleontology 39(3). Taylor & Francis: e1617723.
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Longirostrine crocodylians from the Bartonian of Morocco and Paleogene climatic and sea level oscillations in the Peri-Tethys area
The Eocene–Oligocene transition was a period of high faunal and floral turnover, often correlated with climatic deterioration. Crocodyliforms are climate sensitive, and they have been often used for reconstruction of paleoclimates. The description of crocodylian material from the Bartonian of Aaiun-Tarfaya Basin (Morocco) allows the recognition of at least two longirostrine crocodylians, including a gavialoid. This identification is important, because the migration of gavialoids to South America probably occurred during the late Eocene. Close relationships between late Eocene–early Oligocene Eogavialis africanum from Egypt, Argochampsa krebsi from the Paleocene of Morocco, and the South American gavialoid clade suggests that Morocco could have had a particular place in the gavialoid dispersal route to South America. The resemblance between Moroccan material described herein and E. africanum is thus important in this context. Analysis of the distribution of longirostrine crocodylians in the Peri-Tethys area through the Eocene–Oligocene shows a strong difference in the evolution of the distribution between longirostrine crocodylians and Diplocynodon. Whereas the freshwater Diplocynodon has a continuous distribution in western Europe, the mainly marine longirostrine crocodylians have a northern maximal expansion that moves southward during the middle Eocene, being restricted to North Africa during late Eocene–early Oligocene. European freshwater Asiatosuchus-like taxa also disappear during the late Eocene. Climatic deterioration, helped by sea level oscillations, may have strongly impacted the diversity and latitudinal distribution of the crocodylians, but we highlight a possible differential tolerance in range of climatic conditions between crocodylians. This could help to refine the use of crocodylians as paleoclimatic proxies.
FIGURE 3. Gavialoid remains from Gueran, Morocco. A – D, FSAC BOUJ-405, portion of a left dentary in A, dorsal, B, lateral, C, ventral, and D, posterior views. E – G, FSAC BOUJ-401, FSAC BOUJ-402, FSAC BOUJ-403, FSAC BOUJ-404, and FSAC BOUJ-407, fragmentary snout in E,
ventral, F, left lateral, and G, dorsal views. H, FSAC BOUJ-401, 11th left maxillary tooth in lateral view. I, FSAC BOUJ-401, 13th left maxillary
tooth in lateral view. J, FSAC BOUJ-402, 13th right maxillary tooth in lateral view. Abbreviations: Ectp, ectopterygoid; MX-J, maxillojugal contact;
Pl, palatine; Pmx, premaxilla; SoF, suborbital fenestra. Scale bars equal 1 cm.
Latest publications, 2018
Title
Zouhri, Samir, Philip Gingerich, Sylvain Adnet, et al. 2018. Middle Eocene Vertebrates from the Sabkha of Gueran, Atlantic Coastal Basin, Saharan Morocco, and Their Peri-African Correlations. Comptes Rendus Geoscience 350(6): 310–318.
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Middle Eocene vertebrates from the sabkha of Gueran, Atlantic coastal basin, Saharan Morocco, and their peri-African correlations
The sabkha of Gueran in the Southwest Moroccan Sahara has yielded a rich and diverse fauna of late middle Eocene vertebrates that include the world's richest Bartonian age archaeocete assemblage. Archeocete remains were described previously and here we report on the rest of the vertebrate fauna. The Gueran fauna includes abundant chondrichthyan species belonging to Lamniformes, Carcharhiniformes and Rhinopristiformes, and actinopterygian assemblage consisting of Cylindracanthus, of a siluriform, and of Perciformes. Turtles are represented by at least two marine taxa referred to as Cheloniidae and Dermochelyidae. Crocodylian remains belong to at least two longirostrine species, including gavialoid remains. Snakes are represented by Pterosphenus cf. schweinfurthi (Palaeophiidae). Seabirds are represented by a pseudo-toothed bird (Pelagornithidae). The avian fossil belonged to a gigantic soaring bird and constitutes the earliest occurrence of the genus Pelagornis. The presence of proboscideans is attested by dental fragments. This fossil assemblage from Gueran shows affinities with those of the Eocene beds of Egypt and Libya. The numerous shared taxa support a close biogeographical connection between faunas from southeastern and southwestern coasts of the Mediterranean Sea.
Latest publications, 2017
Title
Jouve, S., Sarıgül, V., Steyer, J.-S., Sen, S., 2017. The first crocodylomorph from the Mesozoic of Turkey (Barremian of Zonguldak) and the dispersal of the eusuchians during the Cretaceous. Journal of Systematic Palaeontology 1–18. https://doi.org/10.1080/14772019.2017.1393469
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The first crocodylomorph from the Mesozoic of Turkey (Barremian of Zonguldak) and the dispersal of the eusuchians during the Cretaceous.
A new crocodylomorph from the upper Barremian _ Incigez Formation of Zonguldak (NW Turkey) is described for the first time based on jaw and limb bone elements from the collection of the Istanbul Technical University. The material is attributed to Turcosuchus okani gen. et sp. nov. according to a unique combination of character states, such as a strong heterodonty, composed of non-spatulated teeth, a maximum of 10 teeth posterior to the symphysis, a sigmoidal dorsal margin of the dentary in lateral view, and a splenial excluded from the symphysis. An updated phylogenetic analysis of crocodylomorphs confirms that this new taxon belongs to the Hylaeochampsidae, and that it forms a relatively robust clade with the derived Unasuchus, Acynodon, Iharkutosuchus and Hylaeochampsa. Turcosuchus also presents some anatomical convergence with bernissartids, allodaposuchids, basal globidontans and other crocodylians. Turcosuchus okani is one of the earliest, but not basal hylaeochampsids, and the first known Early Cretaceous eusuchian outside Europe and North America. Our results support the clear geographical segregation between the Late Cretaceous tribodont eusuchians: basal globidontans in North America, and hylaeochampsids in the Tethyan area.
Turcosuchus okani gen. et sp. nov., holotype, _ IT € U-Z1, anterior portion of the left hemimandible, Barremian, Gelik, Zonguldak district, Turkey, in: A, dorsal; B, dorsolingual; C, labial; and D, ventral views. The hatching indicates the damaged areas and dashed lines denote the inferred orientation of the symphyseal portion. Abbreviations: aio, anterior intermandibularis oralis foramen; ang, angular; a10, 10th preserved tooth alveolus; den, dentary; gasf, groove of the anterior surangular foramen; mg, Meckelian groove; spl, splenial; sur, surangular; t1–9, preserved teeth (1st to 9th).
Title
Jouve, S., Mennecart, B., Douteau, J., Jalil, N.-E., 2017. Biases in the study of relationships between biodiversity dynamics and fluctuation of environmental conditions. Palaeontologia Electronica 20, 1–21.
Journal
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Biases in the study of relationships between biodiversity dynamics and fluctuation of environmental conditions
During the last decades, studies testing the correlations between the dynamics of diversity with various environmental variables strongly increased, but numerous biases affecting these analyses have been recognised. Recent studies considering the evolution of marine crocodylomorphs in comparison with the fluctuations of sea surface temperature and sea level found contradictory results. However, we considered a diversity analysis published two years before our work, and noticed several taxonomical issues (new material and species described since the publication of this paper, unidentified thalattosuchians in time bins where previous analyses considered the absence of any marine crocodylomorphs, and some taxonomical corrections). Here we test the impact of updating the dataset on these results. We also tested the consequences of the time range considered and various methods in reconstructing the sea surface temperature curve.
Each of these corrections and modifications impacts strongly the results, and most of them drive to a different conclusion from the original work. These results point out the crucial importance of taxonomical work in diversity studies to provide reliable results, such as the method used to construct the proxies. The contradictory results obtained here question the reliability of the correlations proposed until now between crocodylomorph evolution and environmental proxies. Deep taxonomic and phylogenetic review should be conducted prior to studying the diversity evolution of a group. This also strongly questions the use of the Paleobiology Database in diversity analyses when the studied group has not yet been reviewed and that numerous, doubtful, nineteenth century species are considered in this dataset.
Title
Jouve, S., 2017. Leiokarinosuchus brookensis, Pholidosaurus meyeri , or Anteophthalmosuchus hooleyi? What is this croc? Journal of Vertebrate Paleontology 37, e1297947. https://doi.org/10.1080/02724634.2017.1297947
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Leiokarinosuchus brookensis, Pholidosaurus meyeri, or Anteophthalmosuchus
hooleyi? What is this croc?
Specimen NHMUK 28966 is a part of the skull of a crocodyliform from the Lower Cretaceous of the Isle of
Wight. It was first described as Pholidosaurus meyeri but was attributed recently to a new genus and species,
Leiokarinosuchus brookensis. The specimen is highly eroded, and most of the characters considered as diagnostic are likely the result of its poor state of preservation. All the observations are biased by the strong erosion of the skull, and consequently, no diagnostic character can be retained for this species. A review of the goniopholidid Anteophthalmosuchus hooleyi, also from the English Wealden, shows that NHMUK 28966 can be attributed to this species. Leiokarinosuchus brookensis is therefore a junior synonym of Anteophthalmosuchus hooleyi. In extant crocodylians, the growth of the occipital condyle is isometric whereas the growth of the foramen magnum is allometric relative to the skull table width. The slopes of the log-transformed data obtained for the holotype of A. hooleyi and BGS GSM 119453, a small specimen previously assigned to cf. Anteophthalmosuchus, are similar to those obtained for two extant species. This confirms observations of anatomical similarities and the attribution of BGS GSM 119453 to A. hooleyi. The new attributions clarify the taxonomic composition of the crocodylomorph assemblage from the Wessex Formation. It is clearly dominated by the large generalist goniopholidid A. hooleyi; the long-snouted morphology was represented by the medium-sized Vectisuchus leptognathus,whereas Theriosuchus sp., Koumpiodontosuchus aprosdokiti, and Hylaeochampsa vectiana are small dietary specialists.
Latest publication, 2016
Title
Jouve, S., Mennecart, B., Douteau, J., Jalil, N.-E., 2016. The oldest durophagous teleosauroid (Crocodylomorpha, Thalattosuchia) from the lower Bathonian of central High Atlas, Morocco. Palaeontology 59, 863–876. https://doi.org/10.1111/pala.12262
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The oldest durophagous teleosauroid (Crocodylomorpha, Thalattosuchia) from the lower Bathonian of central High Atlas, Morocco.
Marine crocodylomorphs were particularly abundant in Europe during the Middle Jurassic, but were very scarce in Africa. New finds of thalattosuchian cranial remains in Morocco suggest that this scarcity is probably
related to poor sampling rather than original diversity. These remains pertain to the coastal thalattosuchians, the teleosauroids, and particularly to the clade grouping the blunt-toothed ‘Steneosaurus’ obtusidens and the genus Machimosaurus. A new tribe is erected grouping these two taxa: Machimosaurini. Until now the machimosaurins have been known from the middle Callovian. The new material extends the presence of this group further back to the lower Bathonian, nearly 5 myr earlier. The machimosaurins are the only teleosauroid group that has been recently reviewed, and the difference between the revised diversity provided herein and that previously reported is large. A review of other teleosauroids and clear establishment of their phylogenetic relationships are also likely to have considerable impact on their observed diversity. So, until a complete review of the teleosauroids is carried out, the results of crocodylomorph diversity analyses should be treated with caution.
Phylogenetic relationships, stratigraphical and temporal distribution, and specific diversity counts of the machimosaurins. The phylogenetic relationships are from Fanti et al. (2016), the suprageneric names, except Machimosaurini, are from the systematic review proposed by Vignaud (1995), and the diversity counts are respectively the observed and phylogenetically corrected diversity.
They include the material described herein and in recent papers (Fanti et al. 2016; Foffa et al. 2015), as recent taxonomic review of Machimosaurus (Young et al. 2014a; Foffa et al. 2015; Fanti et al. 2016). This count is compared with that used in recent diversity analyses (Martin et al. 2014; Mannion et al. 2015; Tennant et al. 2016).
Title
Jouve S. 2016. A new basal tomistomine (Crocodylia, Crocodyloidea)from Issel (Middle Eocene; France): palaeobiogeography of basal tomistomines and palaeogeographic consequences . Zoological Journal of the Linnean Society, 177: 165-182.
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A new basal tomistomine (Crocodylia, Crocodyloidea)from Issel (Middle Eocene; France): palaeobiogeography of basal tomistomines and palaeogeographic consequences .
Kentisuchus astrei sp. nov., holotype, MHNT.PAL.2010.0.49, skull. Late Lutetian sandstone, Issel, Aude, France.
Phylogenetic relationships, and stratigraphical and temporal distribution of the Eocene tomistomines. A, ‘Tomistoma’coppensi; B, clade Tomistoma schlegelii + G. eggenburgensis + Tomistoma lusitanica; C, clade Tomistoma antiqua + Tomistoma carolinensis; D, clade Tomistoma machikanense + Penghusuchus pani.
Phylogenetic relationships of basal tomistomines and palaeobiogeography. A–E, first hypothesis; A, F–I, second
hypothesis. A, early Ypresian, with Maroccosuchus zennaroi (1 and 1?), cf. Kentisuchus sp. (K?); B, F, middle to late Ypresian with M. zennaroi (1 and 1?), and Kentisuchus spenceri (2); C, G, early Lutetian, with Dollosuchoides densmorei (5), and Tomistominae indet. (T); D, H, late Lutetian, with ‘Tomistoma’ cairense (6) and Kentisuchus astrei sp. nov. (3); E, I,
Bartonian with Megadontosuchus arduini (4) and Paratomistoma courtii (7). Maps modified and redrawn from Ron Blakey (http://www2.nau.edu/rcb7/, updated page: March 2011, Copyright Ron Blakey)
The holotype of ‘A. glareae’, a partial mandible, is lost, and the skull cannot be designated as a lectotype for the species. ‘Atacisaurus glareae’ is thus a nomen dubium. The skull bears a combination of characters, allowing us to assign it to the genus Kentisuchus. It differs from the, until now, only known species Kentisuchus spenceri from the Ypresian of England, in having a more robust snout, with the constriction of the snout at the level of the seventh–eighth teeth being 80% of the largest maxillary width, and not bearing anteroposterior shallow
fossae along the lacrimomaxillary sutures. A new species is thus erected, Kentisuchus astrei sp. nov. Phylogenetic analysis confirms that the genus Kentisuchus is one of the most primitive tomistomine. The phylogenetic and palaeogeographic distribution suggests that Kentisuchus was isolated in the Atlantic Ocean, and Ebro (Spain) and Aquitaine (France) basins, during the Ypresian, and that the south Pyrenean marine corridor between the Atlantic Ocean and the Tethys could have closed during the early Ypresian, earlier than previously supposed. This could be correlated with the first mammal migrations from the Iberian Peninsula to Southern France. The palaeogeographic distribution of early and middle Eocene tomistomines also suggests the possible presence of a marine corridor between the North Sea and the Central Tethys through the Polish Lowlands Basin during the early Lutetian. This marine corridor could be informative for studies on mammal migration, as the presence of a north–south marine corridor necessarily means there is an absence or less efficient east–west terrestrial passage. This could have consequences on the history of Asian–European mammal migrations.
Publication, 2014
Title
Jouve S., Bouya B., Amaghzaz M., & Meslouhd M., In press. Maroccosuchus zennaroi (Crocodylia: Tomistominae), the basalmost tomistomine: phylogenetic and palaeobiogeographic implications. Journal of Systematic Palaeontology.
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Maroccosuchus zennaroi (Crocodylia: Tomistominae), the basalmost tomistomine: phylogenetic and palaeobiogeographic implications.
Maroccosuchus zennaroi from the Ypresian of the Oulad Abdoun Basin (Morocco) is described in detail based on numerous and well preserved specimens.
Maroccosuchus zennaroi Jonet and Wouters, 1977, Ypresian, Ouled Abdoun Basin, Morocco. Photographs of the material described and figured by Arambourg (1934, 1935, 1952).
Maroccosuchus zennaroi Jonet and Wouters, 1977, Ouled Abdoun Basin, Morocco. IRSNB R408, holotype skull in dorsal view (A, C), ‘couche 1’ (layer 1), Ypresian, Sidi Daoui, Ouled Abdoun Basin, Morocco; OCP DEK-GE 385, skull and mandible in dorsal view (B), ‘Couche 1’ (layer 1), Ypresian, Sidi Daoui, Ouled Abdoun Basin, Morocco.
Maroccosuchus zennaroi Jonet and Wouters, 1977, MHNT.PAL.2006.80.11, skull and mandible, Ypresian, Ouled Abdoun Basin, Morocco, (A) in dorsal view, photograph; (B) interpretative drawing.
A phylogenetic analysis including 64 ingroup taxa and 238 characters reveals that M. zennaroi is the basalmost tomistomine. This clade is supported by 10 unambiguous synapomorphies, while only 2 - both related to the snout shape and observed in gavialoids - support a closer relationship between Kentisuchus spenceri and later tomistomines. Their absence in M. zennaroi could reflect its intermediate morphology between basal crocodyloids and longirostrine tomistomines. This clearly indicates a Lower Eocene, and no older than Late Paleocene age for the tomistomine emergence, questioning the Late Eocene, Oligocene, and Miocene ages proposed for Gavialis-Tomistoma divergence by molecular analyses. Considering this analysis, the biogeographic history of the tomistomines is evaluated. This history begins in western Tethys during the Lower Eocene or latest Paleocene, with M. zennaroi followed by several West European tomistomines. The Tethys becomes the centre of dispersal to North America, Africa, and Asia. The phylogenetic analysis also suggests at least two independent dispersals from Tethyan Area to Asia, with the extent Tomistoma schlegelii more closely related to European Miocene forms in the first hand, and Toyotamaphimeya machikanense and Penghusuchus pani more closely related to the North American Thecachampsa in the second hand. But poor number of remains in Oligocene and Late Eocene does not allow to provide clear date of divergence and dispersal routes.
Temporal and palaeogeographic distribution of the tomistomines. (A) consensus tree of tomistomines with temporal distribution; (B) geographic distribution of tomistomines. Legend: black lines, Tethyan area; grey lines, Asia; white lines, Africa; dashed lines, Americas.
