Dinosaur Teeth Research Articles

Diet preferences and climate inferred from oxygen and carbon isotopes of tooth enamel of Tarbosaurus bataar (Nemegt Formation, Upper Cretaceous, Mongolia)

Stable isotopes of oxygen and carbon of tooth enamel are increasingly being used as tracers to study palaeoecology and the diet preferences of fossil vertebrates. We serially sampled tooth enamel carbonate along the growth axes of five Early Maastrichtian carnivorous dinosaur teeth (Tarbosaurus bataar tyrannosaurid) from the Nemegt Formation, Mongolia, in order to identify seasonal climatic variations and determine the diet of this apex predator. Additional bulk samples of dentine, bone, and surrounding sediment were analyzed in order to exclude diagenetic obfuscation of the isotopic record. Enamel samples of potential prey species for dietary studies were also analyzed. In the case of the largest specimens, the sampled teeth usually recorded annual cycles ranging between two-thirds and a full year. Fluctuations in δ18O values in tyrannosaurid teeth suggest seasonality (high annual temperatures with distinct precipitation/humidity maxima during summer months) with mean annual temperatures (MAT) ten degrees higher than those of present-day Mongolia. The seasonal pattern of δ18O shows similarities to that of the modern-day Shijiazhuang Global Network of Isotopes in Precipitation station, northern China, and suggests that the Nemegt biota flourished when exposed to a cool temperate monsoon-influenced climate. Herbivore and carnivore carbon isotopes (δ13C) values from tooth enamel imply the presence of a woodland ecosystem dominated by coniferous trees such as Araucariaceae, and are consistent with the hypothesis that large sauropods and hadrosaurids were the preferred prey of Tarbosaurus. Mean annual precipitation (MAP), based on the relationship between modern-day C3 gymnosperms and local average MAP, is estimated at 775–835 mm/yr. These results show that large theropod teeth can serve as valuable archives for palaeoenvironmental studies.

New theropod dinosaur teeth from the Middle Jurassic of the Isle of Skye, Scotland

The Middle Jurassic is a largely mysterious interval in dinosaur evolution, as few fossils of this age are known worldwide. In recent years, the Isle of Skye has yielded a substantial record of trackways, and a more limited inventory of body fossils, that indicate a diverse fauna of Middle Jurassic dinosaurs living in and around lagoons and deltas. Comparatively little is known about the predators in these faunas (particularly theropod dinosaurs), as their fossils are among the rarest discoveries. We here report two new isolated theropod teeth, from the Valtos Sandstone Formation and Lealt Shale Formation of Skye, which we visualized and measured using high-resolution x-ray computed microtomographic scanning (µCT) and identified via statistical and phylogenetic analyses of a large comparative dental dataset. We argue that these teeth most likely represent at least two theropod species – one small-bodied and the other large-bodied – which likely belonged to one or several clades of basal avetheropods (ceratosaurs, megalosauroids, or allosauroids). These groups, which were diversifying during the Middle Jurassic and would become dominant in the Late Jurassic, filled various niches in the food chain of Skye, probably both on land and in the lagoons. Supplementary material : Character lists, datasets, and measurements are available at https://doi.org/10.6084/m9.figshare.c.4452533

Spinosaurid teeth from the Lower Cretaceous of Ko Kut, eastern Thailand

Isolated theropod dinosaur teeth from Ko Kut (Kut Island) in eastern Thailand are referred to an indeterminate spinosaurid on the basis of their morphology and ornamentation. On the basis of other spinosaurid occurrences in Thailand and other parts of Asia, they support the attribution of the fossil-bearing beds on Ko Kut to the Lower Cretaceous rather than the Jurassic. The lack of ornithischian remains in the Ko Kut faunal assemblage suggests that it is coeval with the Sao Khua Formation (Barremian) of NE Thailand.

A new microvertebrate assemblage from the Mussentuchit Member, Cedar Mountain Formation: insights into the paleobiodiversity and paleobiogeography of early Late Cretaceous ecosystems in western North America.

The vertebrate fauna of the Late Cretaceous Mussentuchit Member of the Cedar Mountain Formation has been studied for nearly three decades, yet the fossil-rich unit continues to produce new information about life in western North America approximately 97 million years ago. Here we report on the composition of the Cliffs of Insanity (COI) microvertebrate locality, a newly sampled site containing perhaps one of the densest concentrations of microvertebrate fossils yet discovered in the Mussentuchit Member. The COI locality preserves osteichthyan, lissamphibian, testudinatan, mesoeucrocodylian, dinosaurian, metatherian, and trace fossil remains and is among the most taxonomically rich microvertebrate localities in the Mussentuchit Member. To better refine taxonomic identifications of isolated theropod dinosaur teeth, we used quantitative analyses of taxonomically comprehensive databases of theropod tooth measurements, adding new data on theropod tooth morphodiversity in this poorly understood interval. We further provide the first descriptions of tyrannosauroid premaxillary teeth and document the earliest North American record of adocid remains, extending the appearance of this ancestrally Asian clade by 5 million years in western North America and supporting studies of pre-Cenomaninan Laurasian faunal exchange across Beringia. The overabundance of mesoeucrocodylian remains at the COI locality produces a comparatively low measure of relative biodiversity when compared to other microvertebrate sites in the Mussentuchit Member using both raw and subsampling methods. Much more microvertebrate research is necessary to understand the roles of changing ecology and taphonomy that may be linked to transgression of the Western Interior Seaway or microhabitat variation.

Incremental growth of therizinosaurian dental tissues: implications for dietary transitions in Theropoda.

Previous investigations document functional and phylogenetic signals in the histology of dinosaur teeth. In particular, incremental lines in dentin have been used to determine tooth growth and replacement rates in several dinosaurian clades. However, to date, few studies have investigated the dental microstructure of theropods in the omnivory/herbivory spectrum. Here we examine dental histology of Therizinosauria, a clade of large-bodied theropods bearing significant morphological evidence for herbivory, by examining the teeth of the early-diverging therizinosaurian Falcarius utahensis, and an isolated tooth referred to Suzhousaurus megatherioides, a highly specialized large-bodied representative. Despite attaining some of the largest body masses among maniraptoran theropod dinosaurs, therizinosaurian teeth are diminutive, measuring no more than 0.90 cm in crown height (CH) and 0.38 cm in crown base length (CBL). Comparisons with other theropods and non-theropodan herbivorous dinosaurs reveals that when controlling for estimated body mass, crown volume in therizinosaurians plots most closely with dinosaurs of similar dietary strategy as opposed to phylogenetic heritage. Analysis of incremental growth lines in dentin, observed in thin sections of therizinosaurian teeth, demonstrates that tooth growth rates fall within the range of other archosaurs, conforming to hypothesized physiological limitations on the production of dental tissues. Despite dietary differences between therizinosaurians and hypercarnivorous theropods, the types of enamel crystallites present and their spatial distribution—i.e., the schmelzmuster of both taxa—is limited to parallel enamel crystallites, the simplest form of enamel and the plesiomorphic condition for Theropoda. This finding supports previous hypotheses that dental microstructure is strongly influenced by phylogeny, yet equally supports suggestions of reduced reliance on oral processing in omnivorous/herbivorous theropods rather than the microstructural specializations to diet exhibited by non-theropodan herbivorous dinosaurs. Finally, although our sample is limited, we document a significant reduction in the rate of enamel apposition contrasted with increased relative enamel thickness between early and later diverging therizinosaurians that coincides with anatomical evidence for increased specializations to herbivory in the clade.

Stable Isotopes Reveal Rapid Enamel Elongation (Amelogenesis) Rates for the Early Cretaceous Iguanodontian Dinosaur Lanzhousaurus magnidens

Lanzhousaurus magnidens, a large non-hadrosauriform iguanodontian dinosaur from the Lower Cretaceous Hekou Group of Gansu Province, China has the largest known herbivorous dinosaur teeth. Unlike its hadrosauriform relatives possessing tooth batteries of many small teeth, Lanzhousaurus utilized a small number (14) of very large teeth (~10 cm long) to create a large, continuous surface for mastication. Here we investigate the significance of Lanzhousaurus in the evolutionary history of iguanodontian-hadrosauriform transition by using a combination of stable isotope analysis and CT imagery. We infer that Lanzhousaurus had a rapid rate of tooth enamel elongation or amelogenesis at 0.24 mm/day with dental tissues common to other Iguanodontian dinosaurs. Among ornithopods, high rates of amelogenesis have been previously observed in hadrosaurids, where they have been associated with a sophisticated masticatory apparatus. These data suggest rapid amelogenesis evolved among non-hadrosauriform iguanodontians such as Lanzhousaurus, representing a crucial step that was exapted for the evolution of the hadrosaurian feeding mechanism.

Evolutionary implications of tooth attachment versus tooth implantation: A case study using dinosaur, crocodilian, and mammal teeth

ABSTRACTTooth attachment and implantation are two classical descriptors of dental anatomy. Tooth attachment distinguishes between teeth that are either fused to the jaw by bone, or suspended within a socket by a periodontal ligament. Tooth implantation describes the geometry of this attachment and has been broadly divided into acrodonty, pleurodonty, and thecodonty. Among extant amniotes, only mammals and crocodilians are considered truly thecodont, because they possess a complex attachment system that includes a periodontal ligament and true tooth sockets. These two amniote groups diverged from a common ancestor over 300 million years ago and are thought to have evolved thecodonty independently. This view has recently come under a great deal of scrutiny with the discovery of complex tooth attachment systems, including the presence of a ligamentous tooth attachment in numerous non-mammalian, non-crocodilian amniotes. This has spurred debate and inconsistencies over the conventional usage of tooth attachment and implantation categories and their evolutionary significance. We provide a comparative histological approach for describing tooth attachment and implantation in an exemplary, traditionally thecodont taxonomic group: the non-avian dinosaurs. The comparisons between theropod, hadrosaurid, and ceratopsid teeth show that all dinosaurs have ligamentous tooth attachments composed of identical dental tissues to those in mammals and crocodilians, but they show a diverse array of tooth attachment geometries, replacement modes, and bone architectures supporting the dentition. The methodology we follow allows researchers to tease apart phylogenetically and functionally significant features of tooth attachment and implantation that could be used in future studies.Citation for this article: LeBlanc, A. R. H., K. S. Brink, T. M. Cullen, and R. R. Reisz. 2017. Evolutionary implications of tooth attachment versus tooth implantation: a case study using dinosaur, crocodilian, and mammal teeth. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1354006.

Morphometry, Microstructure, and Wear Pattern of Neornithischian Dinosaur Teeth From the Upper Cretaceous Iharkút Locality (Hungary).

Teeth of iguanodontian ornithopods and ceratopsians could be remarkably similar, thus the referral of isolated dental material to particular neornithischian clades can be highly problematic. These groups are represented by the rhabdodontid Mochlodon vorosi and the basal coronosaurian Ajkaceratops kozmai in the Upper Cretaceous Csehbánya Formation at Iharkút (western Hungary). Whereas teeth of Mochlodon are common elements at the locality, no dental material belonging to Ajkaceratops was identified until now. Here we used mathematical statistical approaches, as well as tooth wear and dental microstructure analysis in order to decide whether the teeth previously referred to Mochlodon can be treated as a homogenous sample, or some remains belong rather to Ajkaceratops. According to our results, there was a striking morphological and structural convergence between the teeth of both taxa. However, the wear study revealed the existence of two different patterns within the sample. One is characterized by straight and parallel microstriations that suggest orthal movements during the jaw closure. This pattern was associated with Mochlodon. The other pattern appeared only on a few teeth, and it can be differentiated by its distinctive curved microstriations that indicate circumpalinal chewing. Because curved striations have never been described in ornithopods, but are found in several neoceratopsians, this pattern was associated here with Ajkaceratops. Here we present the first teeth that can provisionally be referred to the latter genus. We believe that the methodology discussed in this article will facilitate distinguishing ceratopsian and ornithopod teeth in other localities as well. Anat Rec, 300:1439-1463, 2017. © 2017 Wiley Periodicals, Inc.

Dental histology of Coelophysis bauri and the evolution of tooth attachment tissues in early dinosaurs.

Studies of dinosaur teeth have focused primarily on external crown morphology and thus, use shed or in situ tooth crowns, and are limited to the enamel and dentine dental tissues. As a result, the full suites of periodontal tissues that attach teeth to the jaws remain poorly documented, particularly in early dinosaurs. These tissues are an integral part of the tooth and thus essential to a more complete understanding of dental anatomy, development, and evolution in dinosaurs. To identify the tooth attachment tissues in early dinosaurs, histological thin sections were prepared from the maxilla and dentary of a partial skull of the early theropod Coelophysis bauri from the Upper Triassic (Rhaetian- 209-201 Ma) Whitaker Quarry, New Mexico, USA. As one of the phylogenetically and geologically oldest dinosaurs, it is an ideal candidate for examining dental tissues near the base of the dinosaurian clade. The teeth of C. bauri exhibited a fibrous tooth attachment in which the teeth possessed five tissues: enamel, dentine, cementum, periodontal ligament (PDL), and alveolar bone. Our findings, coupled with those of more recent studies of ornithischian teeth, indicate that a tripartite periodontium, similar to that of crocodilians and mammals, is the plesiomorphic condition for dinosaurs. The occurrence of a tripartite periodontium in dinosaurs adds to the growing consensus that the presence of these tissues is the plesiomorphic condition for the major amniote clades. Furthermore, this study establishes the relative timing of tissue development and growth directions of periodontal tissues and provides the first comparative framework for future studies of dinosaur periodontal development, tooth replacement, and histology. J. Morphol. 277:916-924, 2016. © 2016 Wiley Periodicals, Inc.

PRELIMINARY INVESTIGATION OF SEASONAL PATTERNS RECORDED IN THE OXYGEN ISOTOPE COMPOSITIONS OF THEROPOD DINOSAUR TOOTH ENAMEL

Abstract Oxygen isotope compositions of tooth enamel increments in theropod dinosaurs are investigated as potential proxies of climate seasonality. Six teeth of large carnivorous theropods collected from four Cretaceous formations deposited under contrasted climates have been sampled. These teeth have been analyzed for the oxygen isotope compositions of their apatite phosphate (δ18Op) through incremental sampling performed along the major growth axis. Significant fluctuations in oxygen isotope compositions along the growth axis of each tooth are observed and interpreted as reflecting seasonality in ingested local surface water δ18Ow values. Fluctuations in δ18Op values of theropod teeth from the Aptian of Thailand and Cenomanian of Morocco vary similarly to meteoric water δ18Omw values occurring today in sub-tropical regions subjected to large seasonal amounts of precipitations. A dinosaur tooth recovered from the more inland and mid-latitude Nemegt Formation of Mongolia shows a seasonal pattern similar t...

Evolution and Function of Dinosaur Teeth at Ultramicrostructural Level Revealed Using Synchrotron Transmission X-ray Microscopy.

The relationship between tooth form and dietary preference is a crucial issue in vertebrate evolution. However, the mechanical properties of a tooth are influenced not only by its shape but also by its internal structure. Here, we use synchrotron transmission X-ray microscopy to examine the internal microstructures of multiple dinosaur teeth within a phylogenetic framework. We found that the internal microstructures of saurischian teeth are very different from advanced ornithischian teeth, reflecting differences in dental developmental strategies. The three-tissue composition (enamel–mantle dentin–bulk dentin) near the dentinoenamel junction (DEJ) in saurischian teeth represents the primitive condition of dinosaur teeth. Mantle dentin, greatly reduced or absent from DEJ in derived ornithischian teeth, is a key difference between Saurischia and Ornithischia. This may be related to the derived herbivorous feeding behavior of ornithischians, but interestingly, it is still retained in the herbivorous saurischian sauropods. The protective functions of mantle dentin with porous microstructures between enamel and bulk dentin inside typical saurischian teeth are also discussed using finite-element analysis method. Evolution of the dental modifications in ornithischian dinosaurs, with the absence of mantle dentin, may be related to changes in enamel characteristics with enamel spindles extending through the DEJ.

Developmental and evolutionary novelty in the serrated teeth of theropod dinosaurs.

Tooth morphology and development can provide valuable insights into the feeding behaviour and evolution of extinct organisms. The teeth of Theropoda, the only clade of predominantly predatory dinosaurs, are characterized by ziphodonty, the presence of serrations (denticles) on their cutting edges. Known today only in varanid lizards, ziphodonty is much more pervasive in the fossil record. Here we present the first model for the development of ziphodont teeth in theropods through histological, SEM, and SR-FTIR analyses, revealing that structures previously hypothesized to prevent tooth breakage instead first evolved to shape and maintain the characteristic denticles through the life of the tooth. We show that this novel complex of dental morphology and tissues characterizes Theropoda, with the exception of species with modified feeding behaviours, suggesting that these characters are important for facilitating the hypercarnivorous diet of most theropods. This adaptation may have played an important role in the initial radiation and subsequent success of theropods as terrestrial apex predators.

Was triceratops in need of a good dentist?

Dinosaur Dentition Reptiles and mammalian herbivores tend to differ in the way their teeth align. Ericksson et al. combined nanomechanics and paleontology to study the dental structure of herbivorous dinosaurs. Triceratops and duckbilled dinosaur teeth evolved for efficient chewing of plant matter,

On the spinosaurid theropod teeth from the early Barremian (Early Cretaceous) Blesa Formation (Spain)

Spinosaurids are one of the most abundant theropods from the Early Cretaceous of the Iberian Peninsula. The published fossil record consists mainly of teeth. A good example is La Cantalera-1 site in the Blesa Formation (Spain). This site represents a marshy environment with periodic droughts, resulting in a non-permanent body of water. Theropod dinosaur teeth are frequent. Seventeen spinosaurid teeth have been studied using qualitative and quantitative features, including a statistical analysis, in order to compare them with the known spinosaurid record from Spain. In La Cantalera-1 we recognise two different morphotypes: Baryonychinae indet. and Spinosaurinae? indet. Baryonychinae indet. was produced by baryonychines close to Baryonyx; teeth with similar morphology have been described in other sites from the Early Cretaceous of the Iberian Peninsula. Teeth tentatively attributed to Spinosaurinae? indet. were produced by spinosaurines close to Spinosaurus. This morphotype could provide new evidence of the presence of spinosaurines in the Early Cretaceous of the Iberian Peninsula. The small size of the teeth from La Cantalera-1 when compared with those from other sites is interpreted as the result of the conditions characteristic of the deposit area, which represents an ecosystem unable to sustain large-sized organisms.

A new species of Sinamia (Amiiformes, Sinamiidae) from the Early Cretaceous of Lanzhou Basin, Gansu, China

ABSTRACTA new species of Sinamia is described from fluvial-lacustrine deposits in southern Gansu Province, China. The type material consists of multiple specimens that were recovered in three large blocks, two containing over 60 individuals preserved on a single bedding plane. In addition, material from two other localities is referred to this taxon. One of these contains disarticulated remains of numerous individuals preserved in a single bedding plane. Material from the other locality, from a different region of Gansu, was collected years previously and consists of a block with multiple specimens previously attributed to Sinamia zdanskyi. We interpret the preservation of specimens from all three localities as resulting from the fish becoming isolated in a restricted area, possibly made seasonally inhabitable during flooding, that then was cut off from the main channel forming a small temporary lake or pond that eventually dried out, leaving the fish to be concentrated in a steadily shrinking water body. The covering sediments that preserved these fish were possibly deposited by a subsequent flood not long after the mass-death event. The type locality includes only Sinamia, but the other two localities include remains of a small turtle. The locality containing disarticulated remains also includes isolated crocodile and dinosaur teeth, suggesting that this locality is a crevasse splay. A phylogenetic analysis including the new species supports the monophyly of Sinamiidae, but not the monophyly of Sinamia.http://zoobank.org/urn:lsid:zoobank.org:pub:B60AF989-2CA1-444EACE1-7A9EC6263BFE

Unusual replacement of biogenic apatite by aluminium phosphate phases in dinosaur teeth from the Early Cretaceous of Spain

Altered iguanodontian dinosaur teeth have been studied to analyse the unusual replacement of biogenic apatite and to deduce how the alterations affect the preservation of these fossils. The fossils were recovered from alluvial lacustrine facies (Barremian, Early Cretaceous) in Teruel (Spain). Mandibular teeth and sediments were studied in hand sample, by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The combination of the different techniques shows that the teeth have undergone at least three pseudomorphic stages: (1) replacement of the organic component of the dentine and enamel by fluorapatite; (2) replacement of the fluorapatite by aluminium sulphate phosphate phases (crandallite–woodhouseite series); and (3) replacement of part of the tooth by gypsum and Al- and Fe-rich phosphates (vauxite) as a consequence of the superficial weathering of the fossil-rich outcrop. The presence of organic matter and sulphides in the host rocks was the main factor promoting the dissolution of the previous phases and crystallization of the new ones. This is the first description of the replacement of biogenic apatite in dinosaur teeth by aluminium and iron phosphates as a result of fossil diagenetic processes; these minerals are scarce in sedimentary environments and may have economic interest because they contain rare earth or radioactive elements. Additionally, our results indicate that, to ensure proper curating of the specimens from this fossil site, it is crucial to completely remove the host rock and strictly control storage humidity.

Fluvial transport potential of shed and root-bearing dinosaur teeth from the late Jurassic Morrison Formation.

Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors.

Dinosaur teeth from the Jurassic Qigu and Shishugou Formations of the Junggar Basin (Xinjiang/China) and their paleoecologic implications

The Middle and early Late Jurassic Qigu and Shishugou Formations of the southern and central Junggar Basin yielded teeth of theropods (Theropoda indet.), sauropods (Eusauropoda indet.), and stegosaurs. The dinosaur assemblage of the southern Junggar Basin is less diverse and is represented by smaller forms than in the central part of the basin. The microwear of the teeth of Eusauropoda indet. resembles that observed in Camarasaurus and may have formed as a result of biting through resistant woody materials. Carbon and oxygen isotope data of the sauropod and theropod teeth indicate feeding within a C3-plant ecosystem in a continental setting. Differences in enamel δ13C and δ18O values between Eusauropoda indet. and the theropod teeth are comparable to those observed in other herbivorous and carnivorous vertebrates, and suggest at least partial preservation of original dietary signals.

Evidence of theropod dinosaurs from a Lower Cretaceous karst filling in the northern Sauerland (Rhenish Massif, Germany)

Theropod dinosaur teeth from a Lower Cretaceous karst filling in Devonian reef limestone (Massenkalk) located near the village of Balve on the northern margin of the Rhenish Massif, Germany, are described. Palynological evidence indicates that the karst filling took place during the Late Barremian to (Early) Aptian time interval. Palaeontological excavations carried out during several years at the Balve locality yielded remains of various animal groups, including sharks, amphibians, turtles, crocodiles, pterosaurs, herbivore dinosaurs, and, rarely, mammals. Of particular interest is an assemblage of different theropod dinosaur teeth, which has been characterized with the help of dental comparative morphometry. Based on these analyses, the teeth material from the Balve excavation can be assigned to five morphological groupings including dromaeosaurid and tyrannosauroid theropods. Morphological comparison of the theropod dinosaur teeth record with finds from other fossil localities in western and northwestern Europe of similar age shows clear similarities, but also some distinct differences.

A new Late Cretaceous vertebrate fauna from the Cauvery Basin, South India: implications for Gondwanan paleobiogeography

ABSTRACT Late Cretaceous vertebrate faunas of India are known predominantly from intertrappean deposits in the Deccan volcanic province of the central and western parts of the country. A thick and nearly continuous sequence of Early Cretaceous–Early Paleocene fossiliferous sediments exposed in the Cauvery Basin of South India has been comparatively poorly explored. Here, we present a preliminary description of a new fauna consisting of vertebrate fossils discovered from the continental Upper Cretaceous (late Maastrichtian) Kallamedu Formation. The Kallamedu Fauna includes ganoid fishes, amphibians, turtles, crocodiles, and dinosaurs, with many taxa suggesting Late Cretaceous biotic links between India and other Gondwanan landmasses. Teeth of abelisaurid dinosaurs, known previously from the Middle Jurassic of South America and the Late Cretaceous of Africa, Madagascar, and central and western India, support a pan-Gondwanan distribution for this group of theropod dinosaurs. Of greatest significance, however, is the first discovery of a Simosuchus-like notosuchian crocodile outside of Madagascar. This report of the first Indian Simosuchus-like notosuchian crocodile further strengthens earlier evidence from other vertebrate groups for close biotic links between India and Madagascar in the Late Cretaceous, most likely through dispersal via the Seychelles block, Amirante Ridge, and Providence Bank.