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The evolution of thermometabolism in pseudosuchians (Late Triassic to the present) remains a partly unsolved issue: extant taxa (crocodilians) are ectothermic, but the clade was inferred ancestrally endothermic. Here we inferred the thermometabolic regime of two neosuchian groups, Goniopholididae (Early Jurassic to Late Cretaceous) and Dyrosauridae (middle Cretaceous to late Eocene), close relatives of extant crocodilians, in order to elucidate the evolutionary pattern across Metasuchia (Early Jurassic to the present), a clade comprising Neosuchia (Early Jurassic to the present) and Notosuchia (Middle Jurassic until the late Miocene). We propose a new integrative approach combining geochemical analyses to infer body temperature from the stable oxygen isotope composition of tooth phosphate and paleohistology and phylogenetic comparative methods to infer resting metabolic rates and red blood cell dimensions. †Dyrosaurus and †Goniopholis share with extant crocodilians similar lifestyles, body forms, bone tissue organization, body temperatures, metabolic rates, and red blood cell dimensions. Consistently, we infer ectothermy for †Dyrosaurus and †Goniopholis with the parsimonious implication of neosuchians and metasuchians being primitively ectothermic.

Dyrosauridae was a successful clade of marine crocodyliforms that survived the Cretaceous–Paleogene biotic crises. The most important taxon from North America is Hyposaurus rogersii, a species firs...

Dyrosaurids were highly specialized, largely marine, relatives of living crocodylians, and one of the few archosaur lineages to survive the K-Pg extinction. Dyrosaurids lived during the Cretaceous to the Eocene and represent a unique combination of morphology and ecology not seen in living crocodylians. Little is known about their endocranial anatomy, leaving many questions about their neurosensory adaptations unaddressed. Recently, µCT (micro-computed tomography) scans were made of a well-preserved skull of Rhabdognathus, a Paleocene dyrosaurid from Mali. This marks the first time the braincase and neurosensory features of a dyrosaurid have been examined using CT. We focus our attention to three specific internal structures: the cranial endocast; the inner ear; and the paratympanic sinuses. The cranial endocast of Rhabdognathus revealed novel features including a unique conformation of its paratympanic system, a prominent dorsal venous system that communicates with the external skull table, extremely enlarged tympanic vestibules that meet at the midline of the endocranium, a prominent spherical cerebrum, and elongate olfactory tracts accounting for half the total endocast length. The bizarre laterally facing lateral Eustachian foramen of dyrosaurids is now understood to be a complex fossa including both a ventrally directed lateral Eustachian foramen and a laterally directed foramen for the basioccipital diverticulum. A novel median pterygopharyngeal canal was discovered connecting the pharynx to the adductor chamber. These revelations require a reinterpretation of the associated external foramina visible on the posterior of the skull in dyrosaurids and potentially their close relatives the pholidosaurids. The olfactory tract terminates in an enlarged olfactory region possessing complex bony projections—a unique morphology perhaps serving to increase surface area for olfaction. The inner ear of Rhabdognathus exhibits characteristics seen in both Pelagosaurus and Gavialis. The vestibule is spherical, as in Gavialis, but is significantly expanded. The semicircular canals are enlarged but pyramidal in shape as in the thalattosuchian Pelagosaurus. The proportion of the cochlear length to total endosseous labyrinth height is roughly 0.5 in Rhabdognathus implying that the hearing capabilities resemble that of thalattosuchians. A suite of expanded sense organs (e.g., bony olfactory lamina; hypertrophied vestibule of the inner ear), and the clear expansion of the cerebrum to a more symmetrical and spherical shape suggest that dyrosaurids possess neuroanatomical modifications facilitating an agile predatory near-shore ecology.

International audience; Following our fieldwork in Paleogene deposits of Togo, we herein report cranial as well as postcranial elements belonging to the family Dyrosauridae. This assemblage is dated to the Late Paleocene (Thanetian) from two quarries in southern Togo. The specimens include a partial skull presenting two large supratemporal fossae and a massive occipital condyle; long and slender isolated teeth; amphicoelous vertebrae including several articulated ones; and two osteoderms devoid of carina. The morphology of the partial skull reveals similarities with some African longirostrine forms such as Rhabdognathus spp., although this attribution cannot be confirmed. Longirostrine forms, known in the late Paleocene and early Eocene of the Iullemmeden basin (Nigeria, Niger, Mali, Algeria) and in the phosphates of Morocco and Tunisia, is only represented in Thanetian levels in Togo. Different palaeoenvironmental settings seem to have characterized the various African basins during the lower Eocene, with consequences for the geographic distribution of dyrosaurids. These dyrosaurid remains confirm the presence of the family in Togo during the Paleocene and underline the fossiliferous potential of the coastal sedimentary basin in Togo and in the bay of Benin.; Suite à nos travaux de terrain dans les dépôts du Paléogène du Togo, nous rapportons des éléments crâniens et post-crâniens appartenant à la famille des Dyrosauridae. Cet assemblage de crocodiliens est daté du Paléocène supérieur (Thanétien) affleurant dans deux carrières au Sud du Togo. Les spécimens décrits sont représentés par un crâne partiel présentant de grandes fosses supratemporales et un condyle occipital massif ; des dents isolées effilées et cannelées; des vertèbres amphicoeles dont plusieurs articulées ; et deux ostéodermes dorsaux sans carène. La morphologie des restes crâniens semble similaire à certaines formes africaines longirostres telles que Rhabdognathus spp., bien qu’une telle attribution générique ne puisse être confirmée. Les formes longirostres, connues au Paléocène supérieur et à l’Eocène inférieur dans le bassin des Iullemmeden (Nigéria, Niger, Mali et Algérie), dans les phosphates du Maroc et de Tunisie, ne sont représentées au Togo qu’au Thanétien. Des évolutions paléoenvironnementales différentes semblent avoir caractérisé les divers bassins d’Afrique à l’Eocène inférieur, et ont probablement influencé la distribution géographique des Dyrosauridae. Ces restes inédits de Dyrosauridae confirment, d’une part, la présence de ce groupe au Paléocène au Togo et accentuent, d’autre part, le potentiel fossilifère du bassin sédimentaire côtier du Togo et des dépôts contemporains de la baie du Bénin.

We describe a partial dyrosaurid skeleton recently prepared out of a limestone block discovered in the 1930s from Danian strata along the Atlantic coast of Senegal. The specimen, from a single individual, comprises nicely preserved elements of the appendicular and axial skeleton from the abdominal and sacral region, which enables us to refine our knowledge on some postcranial characteristics of the Dyrosauridae. Although Dyrosauridae are abundant in early Eocene deposits of North Africa, the present discovery in the Danian of Senegal fills a patchier record early after the K/Pg boundary and provides an important comparative data point with the few other Danian dyrosaurid records such asAtlantosuchusfrom nearby Morocco orGuarinisuchusandHyposaurusfrom Brazil and the USA, respectively.

Although the European dinosaur succession during the latest Cretaceous and its relationship with the Cretaceous-Paleogene (K-Pg) mass extinction has been the focus of recent work, other continental vertebrates, such as crocodylomorphs, have received less attention. The European continental record of crocodylomorphs in general, and of eusuchians in particular, is relatively dense through the Maastrichtian until the K-Pg boundary. Traditionally it has been argued that continental crocodylomorphs were minimally impacted by the K-Pg extinction, but they were substantially affected in Europe with the disappearance of endemic eusuchians such as Hylaeochampsidae, Allodaposuchus and their close relatives, and non-eusuchians such as Doratodon or Theriosuchus. Despite extensive sampling in Danian continental deposits, only scarce fragmentary crocodylomorph remains have been cited. It is not until the late Paleocene and Eocene that a recovery in continental crocodylomorphs is observed. The presence of taxa such as planocraniids, the alligatoroids Diplocynodon and Hassiacosuchus, and stem crocodyloids during this period provide the first reliable continental records of Crocodylia in Europe and is best explained by post-extinction immigration from Asia or North America. By contrast, marine forms such as Thoracosaurus are found on both sides of the K-Pg boundary in Europe. The adaptation of these marine animals to different environments, from shallow seas to more transitional or fluvial environments, could be the key to their success and survival across the K-Pg boundary, as seen in other marine crocodylomorph clades such as Dyrosauridae.

Fossils of dyrosaurid crocodyliforms are limited in South America, with only three previously diagnosed taxa including the short-snouted Cerrejonisuchus improcerus from the Paleocene Cerrejon Formation of north-eastern Colom- bia. Here we describe a second dyrosaurid from the Cerrejon Formation, Acherontisuchus guajiraensis gen. et sp. nov., based on three partial mandibles, maxillary fragments, teeth, and referred postcrania. The mandible has a reduced seventh alveolus and laterally depressed retroarticular process, both diagnostic characteristics of Dyrosauridae. Acherontisuchus guajiraensis is distinct among known dyrosaurids in having a unique combination of craniomandibular characteristics, and postcranial morphology that suggests it may have occupied a more placid, fluvial habitat than most known Old-World dy- rosaurids. Results from a cladistic analysis of Dyrosauridae, using 82 primarily cranial and mandibular characters, sup- port an unresolved relationship between A. guajiraensis and a combination of New- and Old-World dyrosaurids including Hyposaurus rogersii, Congosaurus bequaerti, Atlantosuchus coupatezi, Guarinisuchus munizi, Rhabdognathus keiniensis and Rhabdognathus aslerensis. Our results are consistent with an African origin for Dyrosauridae with multiple dispersals into the New World during the Late Cretaceous and a transi- tion from marine habitats in ancestral taxa to more fluvial habitats in more derived taxa.

The fossil record of dyrosaurid crocodyliforms spans the Late Cretaceous to Middle Eocene of Africa, Asia, Europe, North America, and South America. Prior to this study, specimens from South America have been limited to a few fossils with only two taxa diagnosed. We describe a nearly complete skull and unassociated mandible of a new dyrosaurid, Cerrejonisuchus improcerus gen. et sp. nov., from the Paleocene Cerrejón Formation of northeastern Colombia. The skull of C. improcerus has relatively elongate supratemporal fenestrae and well-developed occipital tuberosities, both diagnostic characteristics of Dyrosauridae. The rostrum of adult C. improcerus comprises 54–59% of the length of the skull, making it the shortest snout of any known dyrosaurid. A cladistic analysis using 82 cranial and mandibular characters for all species of Dyrosauridae known from crania yielded two most-parsimonious cladograms with C. improcerus as the sister taxon to a clade including Arambourgisuchus, Dyrosaurus, Hyposaurus, Congosaurus, Rhabdognathus, Atlantosuchus, and Guarinisuchus. Only Chenanisuchus, Sokotosuchus, and Phosphatosaurus, all known only from Africa, are more primitive within Dyrosauridae. Chenanisuchus from the Paleocene of Morocco, the only other known short-snouted dyrosaurid, is not closely related to C. improcerus and a short-snouted condition appears to have evolved independently at least twice within Dyrosauridae. Our analysis supports an African origin of Dyrosauridae with dispersals to the New World by the Late Cretaceous or earliest Paleocene. The presence of C. improcerus, together with undescribed taxa from the Cerrejón Formation, suggests a radiation of dyrosaurid crocodyliforms, possibly following the K-P boundary, in tropical South America.

(2009). Dyrosaurid remains from the Intertrappean Beds of India and the Late Cretaceous distribution of Dyrosauridae. Journal of Vertebrate Paleontology: Vol. 29, No. 4, pp. 1321-1326.

The discovery of a new dyrosaurid crocodylomorph from the well-dated Palaeocene deposits of northeastern Brazil sheds new light on the evolutionary history of this extinct group of marine crocodylomorphs that have survived the Cretaceous–Palaeogene (K–P) extinction crisis. Guarinisuchus munizi , the most complete member of this group collected in South America so far, is closely related to the African forms, and this fact suggests that dyrosaurids had crossed the Atlantic Ocean before the K–P boundary and dispersed from there to North America and other parts of South America. This discovery also suggests that on the coast of northeastern Brazil, dyrosaurids replaced the pre-existing Late Cretaceous fauna of diversified mosasaurs, a group of marine lizards, after the K–P extinction event, becoming the main predators, together with sharks, in shallow marine Palaeocene environments. More detailed stratigraphic records and detailed dating of the deposits with dyrosaurids are necessary to correlate this particular pattern found in the ancient northeastern Brazilian coast within the evolution of the group, especially in Africa.

International audience; New and nearly complete cranial remains of Pholidosaurus purbeckensis are described on the basis of specimens recovered from the Berriasian locality of Cherves-de-Cognac, France. Two skulls, associated mandibles and a set of dorsal osteoderms are available and allow a refinement of the anatomy of the genus, known otherwise from coeval deposits in Germany and England. Because of its longirostrine morphology, convergent with other crocodylomorph lineages, the phylogenetic relationships of Pholidosaurus are likely to be affected by Long Branch Attraction problems. Various tests of removing/excluding longirostrine lineages confirm that Dyrosauridae have a labile position and that their affinities with Pholidosauridae are weakly supported. Results from comparative anatomy and phylogenetic analyses recover Pholidosaurus as the basalmost member of Pholidosauridae, a group closely related to Goniopholididae. Pholidosaurus is recovered together with abundant remains of Goniopholis and with more limited remains of Theriosuchus. The paleoecology of Pholidosaurus and more generally, of Pholidosauridae, is discussed.

Pholidosauridae was a clade of longirostrine crocodyliforms that radiated across Europe, Asia, Africa and the Americas between the Middle Jurassic to Late Cretaceous. The type genus of this clade, Pholidosaurus, is poorly understood and even the number of valid species referable is uncertain. There is considerable instability in this part of the crocodyliform tree, as previous phylogenetic analyses do not agree upon whether Pholidosauridae is monophyletic or not. Preliminary results based on a first-hand re-scoring of the type specimen of Pholidosaurus purbeckensis for different phylogenetic analyses (both in preparation modifications of published datasets) unfortunately does not resolve this issue. When P. purbeckensis is treated as separate OTU, a monophyletic Pholidosaurus is not recovered. The first matrix finds P. purbeckensis and P. schaumbergensis to be distantly related (i.e. a polyphyletic Pholidosaurus), whereas in the second matrix both Pholidosaurus species form a polytomy with Dyrosauridae and a large clade constituting most of Pholidosauridae (in this matrix the inclusion of P. purbeckensis greatly decreases the level of resolution). The on-going in-depth re-description and re-scoring of English Pholidosaurus specimens will help determine whether the genus is monophyletic. This further descriptive work will provide a platform from which the internal relationships of the Pholidosauridae can be investigated.

A new dyrosaurid is described from the Ypresian of the phosphatic deposits of the Oulad Abdoun Basin of Morocco. It is based on numerous cranial and postcranial remains, allowing an almost complete reconstruction. This new Dyrosaurus species, Dyrosaurus maghribensis sp. nov., is currently only known from Morocco. It differs from D. phosphaticus, present in contemporaneous levels of Algeria and Tunisia, by several autapomorpies, including a smooth dorsal margin of the parietal and widely opened choanae. A phylogenetic analysis, using 47 taxa and 234 morphological characters, shows the dyrosaurids as the sister taxon of pholidosaurids, which include Elosuchus, Sarcosuchus, Terminonaris and Pholidosaurus, and the thalattosuchians. Goniopholididae is a non-monophyletic group; however, if dyrosaurids are not included in the analysis, the result differs and the goniopholidids form a distinct clade. If Thalattosuchia is excluded, both Goniopholididae and Pholidosauridae become paraphyletic assemblages. Thus, phylogenetic problems remain with respect to longirostrine clade, and more attention should be paid to resolving their evolutionary relationships amongst the crocodyliforms. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 148, 603–656.

Dyrosaurus phosphaticus (Thomas 1893) has been described several times, but the poor preservation and the incomplete preparation of the material left this species inadequately described. Further preparation of a specimen referred to this species now allows a complete description of the braincase and its various cranial nerves. Dyrosaurid taxonomy is mainly based on mandibular characters and the complete description of the skull of D. phosphaticus, and comparison with the other known species of the family enables enhancement of other taxonomic characters. An emended diagnosis is given for D. phosphaticus, the only known species of this genus. With this new description, new characteristics that enable comparisons with other crocodyliforms are available. The presence of a distinct anterolateral postorbital process is observed in dyrosaurs, Elosuchus, Terminonaris robusta, some Goniopholis, and, although smaller, in Sarcosuchus imperator. In the dyrosaurids D. phosphaticus and Rhabdognathus, the postorbital participates largely in the dorsal margin of the infratemporal fenestra, as in Elosuchus, S. imperator, and Thalattosuchia. The laterodorsal position of the lateral eustachian foramen in dyrosaurids is similar to those of Elosuchus and thalattosuchians. These characters are not shared by Stolokrosuchus lapparenti (included in the family Elosuchidae with Elosuchus), suggesting that without clear phylogenetic analysis, the creation of the Elosuchidae was premature. A preliminary phylogenetic analysis based on comparisons of D. phosphaticus with other dyrosaurids shows that Phosphatosaurus gavialoides and Sokotosuchus ianwilsoni are the most primitive dyrosaurids, and Rhabdognathus is more closely related to Hyposaurus than to D. phosphaticus.

A well-preserved crocodyliform specimen from the Maastrichtian or Paleocene of Mali preserves the braincase and posterior dermatocranium. It is referred to Dyrosauridae on the basis of several derived features (a prominent anterior process of the postorbital, discrete occipital processes on the exoccipitals, significant quadratojugal contribution to jaw joint) and tentatively referred to Rhabdognathus on the basis of supratemporal fenestra shape. The lacrymal and prefrontal are relatively short compared with those published for other dyrosaurids. The palatines border the internal choanae anteriorly, and the choanae are divided by a midline septum derived from the pterygoids. The prefrontal pillars are mediolaterally broad and contact the palate ventrally. One stapes is preserved in place. The basicranial pneumatic system is very unusual, in that the anterior and posterior branches of the median eustachian canal are both separate at the palatal surface, and the pterygoids form part of the border for the anterior branch. The lateral eustachian openings lie within fossae on the lateral surface of the braincase and face laterally, with a descending process of the exoccipital nearly intersecting the opening. The braincase and surrounding dermal bones are elongate anteroposteriorly, and the postorbital's posterior ramus extends along the posterodorsal margin of the infratemporal fenestra. The quadrate ramus projects ventrally. These observations clarify character optimizations in previous phylogenetic analyses of Crocodyliformes.

New fossils of the giant African crocodyliform Sarcosuchus imperator clarify its skeletal anatomy, growth patterns, size, longevity, and phylogenetic position. The skull has an expansive narial bulla and elongate jaws studded with stout, smooth crowns that do not interlock. The jaw form suggests a generalized diet of large vertebrates, including fish and dinosaurs. S. imperator is estimated to have grown to a maximum body length of at least 11 to 12 meters and body weight of about 8 metric tons over a life-span of 50 to 60 years. Unlike its closest relatives, which lived as specialized piscivores in marginal marine habitats, S. imperator thrived in fluvial environments.

A newly-discovered skeleton of Terminonaris (=Teleorhinus) robusta (=robustus) from the early Turonian marine deposits of east-central Saskatchewan affords the opportunity for a detailed description of the anatomy of this species and its placement in the context of other known species of this genus. The specific diagnosis of T. robusta and the generic diagnosis of Terminonaris are established. Terminonaris robusta differs from the type species T. browni mainly in size-related features. Teleorhinus mesabiensis Erickson, 1969 is placed into the synonymy of Terminonaris robusta. The genus can be diagnosed by features of the anterior end of the snout, suturai relationships of the bones surrounding the orbit, and the structure of the occiput. A phylogenetic analysis based upon data drawn from the new material suggests that Terminonaris is not a pholidosaurid but is, instead, closely related to Dyrosaurus. This analysis continues to support the hypothesis that long-snouted crocodyliforms of the traditi...

Sabinosuchus coahuilensis, n. gen. et sp., is a marine crocodyliform from the Upper Cretaceous Sauz Creek Member or lower part of the Cuevas Creek Member of the Escondido Formation (Maastrichtian) near Sabinas in Coahuila, Mexico. The type specimen exhibits two synapomorphies of family Dyrosauridae: dentary alveolus 7 is reduced in size compared with the eighth, and the mandibular symphysis is nearly as wide as it is high for most of its length. Sabinosuchus coahuilensis is distinguished from all other known members of Dyrosauridae on the basis of three autapomorphic traits: the posterior section of the mandible is distinctly broad and flat, the mandibular rami are considerably longer than the symphysis, and the posterior mandibular alveoli are uniquely arranged. Sabinosuchus coahuilensis joins Hyposaurus rogersii as the second known North American dyrosaurid. Although the two were contemporaneous, they differed notably in rostrum length and shape; S. coahuilensis has a relatively shorter rostrum ...

Two fragmentary marine crocodylian specimens were discovered in Upper Cretaceous marine strata near the town of Sabinas in Coahuila, Mexico. Although exposures are poor in the vicinity of the collection sites, associated ammonites indicate that the specimens were recovered from either the Sauz Creek Member or lower part of the Cuevas Creek Member of the Escondido Formation, and are Maastrichtian in age. The two specimens share several unique features, including a reduced seventh dentary alveolus and flat mandibular rostrum that indicate they pertain to the extinct crocodylian family Dyrosauridae. The two are assigned to the same species, referred to here informally as the "Sabinas dyrosaur." The proportions of the mandible in the Sabinas dyrosaur are unusual. Its rostrum is narrow, but relatively short, and intermediate in form between typical longirostrine and brevirostrine dyrosaurs. The distal end of the mandibular rostrum is uniquely shaped with laterally expanded margins and enlarged, closely spaced, first and second alveoli. Dentary alveoli thirteen through fifteen are grouped together, with the fourteenth alveolus laterally offset and confluent with the thirteenth. The splenials participate in only a small part of the mandibular symphysis, and do not diverge laterally with the dentaries in the mandibular rami. The mandible lacks internal or external mandibular fenestra. These unique features, and unusual combination of character states, indicate that the Sabinas dyrosaur represents a previously unknown species. Based on criteria used to recognize marine reptile feeding guilds, the skull and tooth morphology indicate that the Sabinas dyrosaur had a durophagus diet, and may have preyed on the thin-shelled ammonites that are abundantly preserved in the same deposits. Restoration of the fragmentary skull suggests that the Sabinas dyrosaur had a total body length of about 5 to 6 meters, and was among the largest dyrosaurs known. Although dyrosaurid crocodylians were abundant and diverse in Africa during Late Cretaceous and Paleogene time, the Sabinas dyrosaur represents only the second species thus far known from North America. Its occurrence in Mexico is compatible with an hypothesized trans-Atlantic dispersal event of dyrosaurs from Africa to North America during Late Cretaceous time.

We describe a new record of the dyrosaurid crocodyliform genus Hyposaurus, from the ?Campanian— Maastrichtian Shendi Formation of Sudan, based on a partial mandibular symphysis, two posterior portions of the upper jaw, and a fused frontal bone, all belonging to a single individual. The material can be assigned to Hyposaurus on the basis of the elliptical shape of the mandibular symphysis (wider than high) and the overall flat shape of the mandible. At the same time, the fossil material differs from other species of Hyposaurus in having (1) an enlarged eighth alveolus of the dentary relative to the other alveoli; (2) a reduced interalveolar space between the ninth and tenth alveoli; and (3) a prominent ridge and groove sculpturing on the dorsal side of the mandible along the symphyseal region. However, due to the fragmentary nature of the material, we refrain from drawing any higher-resolution taxonomic conclusions. The occurrence of Hyposaurus within the Shendi Formation represents the first reco...

DYROSAURUS POMEL, 1894 A Type species: Dyrosaurus phosphaticus (Thomas, 1893). Type locality: Lower Eocene (Ypresian), from the phosphates of the north of Djebel Teldja, near Metlaoui, Tunisia. Emended diagnosis: Long and narrow snout, representing 73–75% of the total skull length in adults; 18–23 teeth anterior to the orbits; 23–26 teeth per premaxillary + maxillary upper mid-row; prefrontal– nasal contact longer than lacrimal–nasal; posterior wall of the supratemporal fenestra almost vertical and weakly exposed in dorsal view; posterior margin of skull roof straight in dorsal view; occipital tuberosities moderately developed; interfenestral bar ornamented anteriorly and T-shaped in transverse section; ventral portion of the basioccipital almost vertical, and largely visible in occipital view; dorsal osteoderms thin, ornamented with shallow and wide pits separated by wide and low T-shaped margin in cross-section., Published as part of Jouve, Stéphane, Iarochène, Mohamed, Bouya, Baâdi & Amaghzaz, Mbarek, 2006, A new species of Dyrosaurus (Crocodylomorpha, Dyrosauridae) from the early Eocene of Morocco: phylogenetic implications, pp. 603-656 in Zoological Journal of the Linnean Society 148 (4) on page 605, DOI: 10.1111/j.1096-3642.2006.00241.x, http://zenodo.org/record/5427667, {"references":["Thomas P. 1893. Description de quelques fossiles nouveaux ou critiques des terrains tertiaires et secondairesde la Tunisie recueillis en 1885 et 1886 par M. Philippe Thomas. Exploration Scientifique de la Tunisie. Paris: Imprimerie Nationale."]}

This paper describes a new genus and species of dyrosaurid, Chenanisuchus lateroculi gen. et sp. nov. (Crocodyliformes, Mesoeucrocodylia) from the Thanetien (Late Palaeocene) of the Oulad Abdoun Basin, Morocco. This new taxon has a particularly short snout, as well as widely separated and laterally facing orbits. In the holotype, the mandible exhibits a retroarticular process that is strongly depressed posterior to the glenoid fossa, bringing the ventral margin of the medial wing of the articular to the same level as the ventral margin of the retroarticular process. This feature is shared with Congosaurus bequaerti, Dyrosaurus and isolated dyrosaurid material from Mali and Niger, but is absent in the putative closely related crocodyliforms, such as pholidosaurids and Terminonaris, and could be a dyrosaurid character.

Publisher Summary This chapter discusses the marine crocodilian Hyposaurus in North America. The fossil genus Hyposaurus, a longirostrine mesosuchian crocodilian, is a characteristic and relatively common fossil from marine sediments of Maastrichtian through Danian ages. Its geographic range in the United States now extends from New Jersey to Alabama, in glauconite and chalk facies. A specimen that comprises the most perfectly preserved skull and jaws of Hyposaurus rogersii is analyzed. A diminutive seventh mandibular tooth is present only in the right dentary and it is completely absent from the left. This reduction of the seventh mandibular tooth is a synapomorphy of the Dyrosauridae. The edge of each dentary is slightly festooned. The mandibular symphysis varies from quadrangular to oval in transverse section, and is slightly wider than high. The type specimen of Hyposaurus fraterculus Cope is now known to be a juvenile Thoracosaurus, leaving H. rogersii Owen as the only North American species. It is notable as a marine guide fossil of short stratigraphic range, which does, however, span the Cretaceous-Tertiary boundary. It is found that one well-preserved specimen has yielded remarkably large gastroliths, prompting comparison to those of elasmosaurs, with potential contributions to stability in marine environments.

We describe new dyrosaurid fossils from three localities in Mali, representing strata of Maastrichtian, Paleocene, and Eocene ages. The fossils significantly extend the temporal and geographic ranges of several known dyrosaurid taxa. Rhabdognathus keiniensis and Chenanisuchus lateroculi are identified for the first time from Maastrichtian sediments. Additional material is referred to Phosphatosaurus gavialoides and, tentatively, the genus Sokotosuchus. These discoveries represent the first occurrence of Chenanisuchus and possibly of Sokotosuchus from Mali. Previously unknown morphological character states are incorporated into existing data matrices, reducing the amount of missing data. Phylogenetic analyses largely corroborate prior hypotheses of dyrosaurid relationships, but indicate a need for new characters to resolve the relationships of certain genera and species. The occurrence of both basal (e.g., Chenanisuchus lateroculi) and highly nested (e.g., Rhabdognathus keiniensis) members of Dyrosauridae on both sides of the K/T boundary indicates that dyrosaurid diversification was well underway by the latest Cretaceous, and that most, if not all dyrosaurid species survived the extinction event. The geology of the Mali’s Tilemsi Valley is clarified; some rocks previously assigned to the Iullemmeden Basin actually represent extensions of other basins: the Taoudeni Basin and Gao Trench.

The cranial morphology of Mariliasuchus amarali, a poorly known notosuchian from the Late Cretaceous of Southeastern Brazil, is redescribed based on new material. Its phylogenetic affinities within Crocodylomorpha are evaluated through a parsimony analysis involving 46 taxa and 198 characters. Mariliasuchus is nested well inside the clade Notosuchia, as the sister group of Comahuesuchus, a derived notosuchian from the Late Cretaceous of Argentina. Both taxa share the following unambiguous synapomorphies: ventral half of the lacrimal tapering posteroventrally, not contacting or only slightly contacting the jugal; presence of a large foramen on the lateral surface of the anterior part of the jugal; presence of procumbent premaxillary and anterior dentary alveoli; and ectopterygoids that do not participate of the palatine bar. The presence of procumbent premaxillary teeth, specialized tooth crown morphology, and fore–aft jaw movements suggests that this group presented complex jaw movements related ...

Resume Une combinaison particuliere de caracteres permet de distinguer la famille des Dyrosauridae des autresCrocodiliens. Le genre Hyposaurus, du Cretace terminal americain, qui montre cette combinaison, doit etre rapporte a cette famille, surtout connue par ailleurs dans le Maestrichtien et le Paleogene d'Afrique.

Unterkieferreste des bisher nur aus dem unteren Eozan Tunesiens bekannten grosen dyrosauriden KrokodiliersPhosphatosaurus Bergounioux, 1955, werden aus dem unteren Paleozan von Niger und Mali beschrieben. Zahne aus dem Maastricht Agyptens, die von Gemmellaro beschrieben wurden, werden auch einer ahnlichen Form zugeschrieben. Obwohl zu unvollkommen fur eine spezifische Identifizierung, zeigen dennoch alle diese Reste, das sich diese Gruppe der Dyrosauriden mit kraftiger Schnauze und dicken Zahnen schon fruh differenziert hat. Die Evolution der GattungPhosphatosaurus wurde von einer Verlangerung der Unterkiefersymphyse begleitet.

Wounds on the lower jaw of a mesosuchian crocodilian (Tilemsisuchus lavocati, family Dyrosauridae) from the Eocene of Mali are interpreted as a result of intraspecific fighting. This behavioural feature is known in the males of living crocodilians, and related to territoriality, dominance hierarchy and mating. The occurrence of similar kinds of behaviour in the Dyrosauridae and in the living eusuchians is thus suggested, which in turn points to a considerable antiquity for this behaviour, if it was inherited from a common ancestor.

A revision of the crocodilians from the early Eocene (Ypresian) phosphates of southern Tunisia shows that they all belong to the family Dyrosauridae. Dyrosaurus choumowitchi Bergounioux and D. berneti Bergounioux are shown to be junior synonyms of D. phosphaticus (Thomas), while D. variabilis Bergounioux is considered as a nomen dubium. «Rhabdosaurus» acutirostris Bergounioux is referred to the genus Rhabdognathus Swinton. Phosphatosaurus gavialoides Bergounioux is a large dyrosaurid with a massive skull and a crushing dentition ; its cranial anatomy is described in detail. Dyrosaurus phosphaticus was doubtless a fish-eating form, as also possibly Rhabdognathus acutirostris, while Phosphatosaurus gavialoides may have fed on turtles., Une révision des Crocodiliens des phosphates de l'Eocène inférieur (Yprésien) du Sud tunisien montre qu'ils appartiennent tous à la famille des Dyrosauridae. Dyrosaurus choumowitchi Bergounioux et D. bemeti Bergounioux se révèlent être des synonymes plus récents de D. phosphalicus (Thomas), alors que D. variabilis Bergounioux est considéré comme un nomen dubium. «Rhabdosaurus» acutirostris Bergounioux est rapporté au genre Rhabdognathus Swinton. Phosphatosaurus gavia-loides Bergounioux est un grand Dyrosauridé au crâne massif et à la denture broyeuse ; son anatomie crânienne est décrite en détail. Dyrosaurus phosphaticus était sans doute ichthyophage, ainsi peut-être que Rhabdognathus acutirostris, alors que Phosphatosaurus gavialoides se nourissait peut-être de tortues., Buffetaut Éric. Les Dyrosauridae (Crocodylia, Mesosuchia) des phosphates de l'Eocène inférieur de Tunisie : Dyrosaurus, Rhabdognatus, Phospliatosaurus. In: Géologie Méditerranéenne. Tome 5, numéro 2, 1978. pp. 237-255.

The dyrosaurids of the Iullemmeden Basin (West Africa) are mainly represented by two genera, Hyposaurus and Rhabdognathus. Hyposaurus has been recognized in the Paleocene of Mali and Nigeria with two species, H. nopcsai and H. wilsoni. Diagnostic characters given by previous authors for these species do not enable their distinction from each other, nor from North American species. It is therefore reasonable to consider H. nopcsai and H. wilsoni as nomina dubia. In 1930, Swinton erected the new genus and species Rhabdognathus rarus on the basis of mandibular remains, and Buffetaut referred a skull to this species in 1980. A new skull was described in 2002 by Brochu et al., and referred to Rhabdognathus sp. Unfortunately, it is impossible to refer either skull to the type species, the mandibular remains having no diagnostic characters at the specific level. Thus, R. rarus is a nomen dubium, and two new names are erected for the two skulls: R. keiniensis n. sp. and R. aslerensis n. sp., all the mand...