Cretaceous Mammals Research Articles

A large therian mammal from the Late Cretaceous of South America

Theria represent an extant clade that comprises placental and marsupial mammals. Here we report on the discovery of a new Late Cretaceous mammal from southern Patagonia, Patagomaia chainko gen. et sp. nov., represented by hindlimb and pelvic elements with unambiguous therian features. We estimate Patagomaia chainko attained a body mass of 14 kg, which is considerably greater than the 5 kg maximum body mass of coeval Laurasian therians. This new discovery demonstrates that Gondwanan therian mammals acquired large body size by the Late Cretaceous, preceding their Laurasian relatives, which remained small-bodied until the beginning of the Cenozoic. Patagomaia supports the view that the Southern Hemisphere was a cradle for the evolution of modern mammalian clades, alongside non-therian extinct groups such as meridiolestidans, gondwanatherians and monotremes.

Early Cenozoic increases in mammal diversity cannot be explained solely by expansion into larger body sizes

AbstractA prominent hypothesis in the diversification of placental mammals after the Cretaceous–Palaeogene (K/Pg) boundary suggests that the extinction of non‐avian dinosaurs resulted in the ecological release of mammals, which were previously constrained to small body sizes and limited species richness. This ‘dinosaur incumbency hypothesis’ may therefore explain increases in mammalian diversity via expansion into larger body size niches, that were previously occupied by dinosaurs, but does not directly predict increases in other body size classes. To evaluate this, we estimate sampling‐standardized diversity patterns of terrestrial North American fossil mammals within body size classes, during the Cretaceous and Palaeogene. We find strong evidence for post‐extinction diversity increases in all size classes. Increases in the diversity of small‐bodied species (less than 100 g, the common body size class of Cretaceous mammals, and much smaller than the smallest non‐avialan dinosaurs (c. 400 g)) were similar to those of larger species. We propose that small‐bodied mammals had access to greater energetic resources or were able to partition resources more finely after the K/Pg mass extinction. This is likely to be the result of a combination of widespread niche clearing due to the K/Pg mass extinctions, alongside a suite of biotic and abiotic changes that occurred during the Late Cretaceous and across the K/Pg boundary, such as shifting floral composition, and novel key innovations among eutherian mammals.

A new Cretaceous fossil mammal locality from the Bass Coast of southeastern Australia

Mesozoic mammals from the polar regions of Australian Gondwana are exceptionally rare. The recovery of a partial jaw attributable to the australosphenid Ausktribosphenos nyktos from a new locality along the Bass Coast of Victoria is, therefore, significant because it comes from an uppermost Barremian to lowermost Aptian grit with abundant plant material that differs lithologically from other previously productive laminated sandstone deposits. We interpret this as evidence for a floodplain habitat that was distant from local water bodies. The identification of a new Cretaceous mammal locality in Australia highlights the exciting prospects for future fossil discoveries. Thomas H. Rich [trich@museum.vic.gov.au] Museums Victoria, Melbourne, Victoria, 3001, PO Box 666,Australia Melissa L. Lowery [melissalouiselowery@gmail.com] 82 Williams Street, Inverloch, Victoria, 3996, Australia Michael Hall [mike.hall@monash.edu] School of Earth, Atmosphere and Environment, Monash University, Victoria, 3800, Australia Lesley Kool [koollesley@gmail.com] Museums Victoria, Melbourne, Victoria, 3001, Australia PO Box 666; School of Earth, Atmosphere and Environment, Monash University, Victoria, 3800, Australia Joseph Bevitt [joseph.bevitt@ansto.gov.au] Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, Nsw, 2234, Australia Matt White [fossilised@hotmail.com] University of New England, Armidale, Nsw, 2350, Australia Patricia Vickers-Rich [pat.rich@monash.edu, prich@swin.edu.au] School of Earth, Atmosphere and Environment, Monash University, Victoria, 3800, Australia; Department of Chemistry and Biotechnology, Swinburne University of Science and Technology, Hawthorn, Victoria, 3122, Australia.

New mammals from the Naskal intertrappean site and the age of India’s earliest eutherians

The first Cretaceous mammals described from India were recovered from the Naskal locality, on the southeastern edge of the Deccan Traps Volcanic Province (DTVP), where it is preserved between two basalt flows. Because the DTVP eruptions spanned the Cretaceous-Paleogene boundary (KPB), it is often unknown whether trap-associated fossil sites are latest Cretaceous (Maastrichtian) or early Paleocene in age. The Naskal locality accounts for nearly half of published mammal records from DTVP-associated sediments as well as a host of other vertebrate microfossils. Its age takes on singular importance in the context of mammalian evolution in India and the effects of the end-Cretaceous mass extinction and subsequent evolutionary radiation of placentals. Here we describe two new mammal species, Indoclemensia naskalensis gen. et sp. nov. and I. magnus sp. nov., from Naskal and present evidence from 40 Ar/ 39 Ar geochronology, magnetostratigraphy, and chemostratigraphy of the over- and underlying basalt flows to refine the age of the Naskal locality and nearby Rangapur locality. In conjunction with palynostratigraphy and vertebrate biostratigraphy, these sites can be confidently restricted to a <100 kyr interval spanning the KPB. The most probable 40 Ar/ 39 Ar age is latest Cretaceous (66.136–66.056 Ma), but an earliest Paleogene age cannot be ruled out. We explore the implications of this age assignment for Deccan chemostratigraphy and Deccan volcanism, Cretaceous-Paleogene (K/Pg) mass extinction, Indian mammalian faunal evolution, and the timing of the origin of placental mammals. • New 40 Ar/ 39 Ar geochronology, magnetostratigraphy, chemostratigraphy, and palynofloras from the Naskal and Rangapur sites. • Age of Naskal and Rangapur are likely Maastrichtian, constrained to within 100 kyr of the Cretaceous-Paleogene boundary. • Two new eutherian mammal species from the Naskal site of India are described. • These sites are ‘transitional’ distinctive in biotic composition from older and younger infra - and intertrappean localities.

Early Late Cretaceous mammals from southern Patagonia (Santa Cruz province, Argentina)

The Upper Cretaceous (Cenomanian) Mata Amarilla Formation in western central Santa Cruz province of Argentina has yielded fragmentary teeth of a large ?docodontan, an australosphenidan, a meridiolestidan (Amarillodon meridionalis gen. et sp. nov.), and a stem dryolestid (Treslagosodon shehuensis gen. et sp. nov.). These represent the first possible records for docodontans, Cretaceous australosphenidans, and stem dryolestids in South America. Both ?docodontan tooth fragments are unusually large and exhibit potential durophagous adaptation. The Amarillodon gen. nov. lower (?deciduous) posterior premolar has a trigonid angulation of 100° and is autapomorphic by a large and exoedaenodont distolabial accessory cusp on the distal cingulid. Both the mesial and distal cingulid are shelf-like. The mesiolabial upper molar fragment of the ausktribosphenid australosphenidan is similar to an upper M1 of aff. ?Bishops from the lower Albian (Lower Cretaceous) of Australia by its large stylar cusp ?C and breached paracone. The lower molar of the new stem dryolestid is characterized by a large talonid cusp d and a mesio-distally strongly compressed mesial root that is weaker than the distal one. The australosphenidan, if corroborated, suggests faunal interrelationships between Australia and South America by the late Early/early Late Cretaceous.

Cretaceous mammals of India–Stratigraphic distribution, diversity and intercontinental affinities

Extensive research carried out on the Cretaceous deposits of Laurasia has revealed an overwhelming presence of eutherian, metatherian and multituberculate groups of mammals in the Cretaceous ecosystems of Northern Hemisphere continents. In contrast, the relatively poorly documented fossil record of Cretaceous mammals from Gondwanan continents is represented by gondwanatherians, dryolestoids, and a few multituberculates and haramiyidans. Until now, no undoubted eutherian mammals have been reported from the Cretaceous strata of the southern continents except for India. In this context, Indian Cretaceous mammals assume great significance for understanding the origin and evolution of these mammals in Gondwana. Currently, the Cretaceous mammals of India include three groups, viz., eutherians, gondwanatherians, and haramiyidans. These three mammalian groups were recovered primarily from the Upper Cretaceous Deccan infra–and inter–trappean beds of peninsular India exposed near Bacharam, Naskal and Rangapur (Telengana), Upparhatti (Karnataka) and Kisalpuri (Madhya Pradesh) villages. Eutheria is by far the most diverse clade comprising three named genera (Deccanolestes, Sahnitherium, Kharmerungulatum) and one unnamed taxon (Eutheria incertae sedis). The gondwanatherians are known by Bharattherium bonapartei and Sudamericidae gen. et sp. indet. The third mammalian group, a possible haramiyidan, is represented by a solitary species Avashishta bacharamensis. Overall, the Cretaceous mammal fauna of India presents a complex biogeographic history with eutherians of Laurasian affinity, pan–Gondwanan gondwanatherians and a possible late surviving haramiyidan. Numerically abundant and speciose Deccanolestes, identified as an adapisoriculid, has been interpreted to have had originated in northward drifting Indian Plate in the Late Cretaceous and dispersed out of India into Africa and Europe over island arc systems (Oman–Kohistan–Dras) and the Ladakh magmatic arc at or near the Cretaceous–Paleogene boundary. A similar dispersal mode has also been visualized for Kharmerungulatum and Eutheria incertae sedis of Laurasian affinities. The close similarity of dental morphology between Madagascan and Indian gondwanatherians attests to the fact that these taxa derived from a common endemic Gondwanan stock had evolved in isolation following the separation of Indo–Madagascar from other Gondwanan continents. Avashishta represents a late Gondwana survivor of a group that had a Pangaean distribution until the Early Cretaceous.

An enigmatic specialized new eutherian mammal from the Late Cretaceous of Western Europe (Northern Pyrenees)

We report the discovery of a new Late Cretaceous eutherian mammal, Azilestes ragei n. gen., n. sp. from the Mas-d’Azil northern Pyrenean site (France), which is among the largest known. It is only known from a broken lower jaw found in uppermost levels of the Grès de Labarre Formation (early Maastrichtian). Despite its poor preservation, it displays distinctive specialized features with respect to known Cretaceous eutherians. This includes a reduced premolar formula and shortened and robust jaw, an incipient hypolophid, and a cingular-like postcristid and hypoconulid. The phylogenetic analysis suggests indeed a possible stem relationship between Azilestes n. gen. and some clades of herbivorous Cenozoic placentals, but with weak support. Several molar features reminiscent of the Zhelestidae, especially Valentinella Tabuce, Vianey-Liaud &amp; Garcia, 2004, support instead that Azilestes n. gen. is a basal eutherian showing early specialization in a herbivorous diet convergent with some crown placentals. Whatever the suprageneric position of Azilestes n. gen., which remains to be clarified with additional material, its discovery highlights a significant diversity of European Cretaceous eutherians in contrast to their very poor fossil record.

Cretaceous Blind Snake from Brazil Fills Major Gap in Snake Evolution

SummaryBlind snakes (Scolecophidia) are minute cryptic snakes that diverged at the base of the evolutionary radiation of modern snakes. They have a scant fossil record, which dates back to the Upper Paleocene-Lower Eocene (∼56 Ma); this late appearance conflicts with molecular evidence, which suggests a much older origin for the group (during the Mesozoic: 160–125 Ma). Here we report a typhlopoid blind snake from the Late Cretaceous of Brazil, Boipeba tayasuensis gen. et sp. nov, which extends the scolecophidian fossil record into the Mesozoic and reduces the fossil gap predicted by molecular data. The new species is estimated to have been over 1 m long, much larger than typical modern scolecophidians (<30 cm). This finding sheds light on the early evolution of blind snakes, supports the hypothesis of a Gondwanan origin for the Typhlopoidea, and indicates that early scolecophidians had large body size, and only later underwent miniaturization.

Geologically Oldest Pediomyoidea (Mammalia, Marsupialiformes) from the Late Cretaceous of North America, with Implications for Taxonomy and Diet of Earliest Late Cretaceous Mammals

ABSTRACT Terrestrial faunas of Turonian age are poorly known due to the paucity of the fossil record in North America and globally. The Smoky Hollow Member of the Straight Cliffs Formation, southern Utah, has yielded a rich assemblage of terrestrial vertebrates; among these, we herein recognize the geologically oldest members of Pediomyoidea. Two new species, Scalaria martini, gen. et sp. nov. and Scalaria aquilana, gen. et sp. nov., are recovered as members of Aquiladelphidae, sharing upper molar characters such as a subdivided B cusp, round and inflated cusps, and an anteroposteriorly expanded protocone. A fragmentary specimen is recognized as an indeterminate pediomyid with morphological similarities to Leptalestes. The occurrence of these distinctive groups in the Turonian prompted a re-evaluation of possible antecedents from earlier faunas, and a review of specimens referred to Aquiladelphidae. A phylogenetic analysis suggests that the Cenomanian tribosphenidan Dakotadens may belong within Aquiladelphidae. Of specimens referred to Aquiladelphidae, we recognize Aquiladelphis laurae as a valid species within the genus, and describe a new species of Aquiladelphis from the Judith River Formation of Montana, Aquiladelphis analetris, sp. nov. Two specimens from the ‘Edmontonian’ Williams Fork Formation, previously identified as Aquiladelphis, are here referred to a new species of Glasbius, G. piceanus, sp. nov. The presence of dentally derived marsupialiforms in the Turonian suggests that ecological drivers credited with dietary specializations among later Cretaceous taxa, such as proliferation of angiosperms and pollinating insects, were at work earlier than previously thought. http://zoobank.org/urn:lsid:zoobank.org:pub:E938B685-7F91-4BC2-85D6-3CDD501D5D88

Skeleton of aCretaceous mammal from Madagascar reflects long-term insularity.

The fossil record of mammaliaforms (mammals and their closest relatives) of the Mesozoic era from the southern supercontinent Gondwana is far less extensive than that from its northern counterpart, Laurasia1,2. Among Mesozoic mammaliaforms, Gondwanatheria is one of the most poorly known clades, previously represented by only a single cranium and isolated jaws and teeth1-5. As a result, the anatomy, palaeobiology and phylogenetic relationships of gondwanatherians remain unclear. Here we report the discovery of an articulated and very well-preserved skeleton of a gondwanatherian of the latest age (72.1-66million years ago) of the Cretaceous period from Madagascar that we assign to a new genus and species, Adalatherium hui. To our knowledge, the specimen is the most complete skeleton of a Gondwanan Mesozoic mammaliaform that has been found, and includes the only postcranial material and ascending ramus of the dentary known for any gondwanatherian. A phylogenetic analysis including the new taxon recovers Gondwanatheria as the sister group to Multituberculata. The skeleton, which represents one of the largest of the Gondwanan Mesozoic mammaliaforms, is particularly notable for exhibiting many unique features in combination with features that are convergent on those of therian mammals. This uniqueness is consistent with a lineage history for A.hui of isolation on Madagascar for more than 20million years.

A new mammal from the Upper Cretaceous (Turonian–Campanian) Galula Formation, southwestern Tanzania

We here establish a new mammaliaform genus and species, Galulatherium jenkinsi (Mammalia), from the Upper Cretaceous Galula Formation in the Rukwa Rift Basin of southwestern Tanzania. This represents the first named taxon of a mammaliaform from the entire Late Cretaceous of continental Afro-Arabia, an interval of 34 million years. Preliminary study of the holotypic and only known specimen (a partial dentary) resulted in tentative assignation to the Gondwanatheria, a poorly known, enigmatic clade of Late Cretaceous-Paleogene Gondwanan mammals (Krause et al. 2003). The application of advanced imaging (mu CT) and visualization techniques permits a more detailed understanding of key anatomical features of the new taxon. It reveals that the lower dentition consisted of a large, procumbent lower incisor and four cheek teeth, all of which were evergrowing (hypselodont). Importantly, all of the teeth appear devoid of enamel. Comparisons conducted with a range of Mesozoic and selected Cenozoic mammaliaform groups document a number of features (e.g., columnar, enamel-less and evergrowing teeth, with relatively simple occlusal morphology) expressed in Galulatherium that are reminiscent of several distantly related groups, making taxonomic assignment difficult at this time. Herein we retain the provisional referral of Galulatherium (RRBP 02067) to Gondwanatheria; it is most similar to sudamericids such as Lavanify and Bharratherium from the Late Cretaceous of Madagascar and India, respectively, in exhibiting relatively simple, high-crowned, columnar cheek teeth. Other features (e.g., enamel-less dentition) are shared with disparate forms such as the Late Jurassic Fruitafossor and toothed xenarthrans (e.g., sloths), here attributed to convergence. Revised analyses of the depositional context for the holotype place it as having lived sometime between the late Turonian and latest Campanian (roughly 91-72 million years ago). This enhanced geochronological context helps to refine the palaeobiogeographical significance of Galulatherium among Cretaceous mammals in general and those from Gondwanan landmasses specifically.

A Late Cretaceous mammal from Brazil and the first radioisotopic age for the Bauru Group.

In the last three decades, records of tribosphenidan mammals from India, continental Africa, Madagascar and South America have challenged the notion of a strictly Laurasian distribution of the group during the Cretaceous. Here, we describe a lower premolar from the Late Cretaceous Adamantina Formation, São Paulo State, Brazil. It differs from all known fossil mammals, except for a putative eutherian from the same geologic unity and Deccanolestes hislopi, from the Maastrichtian of India. The incompleteness of the material precludes narrowing down its taxonomic attribution further than Tribosphenida, but it is larger than most coeval mammals and shows a thin layer of parallel crystallite enamel. The new taxon helps filling two major gaps in the fossil record: the paucity of Mesozoic mammals in more northern parts of South America and of tribosphenidans in the Cretaceous of that continent. In addition, high-precision U-Pb geochronology provided a post-Turonian maximal age (≤87.8 Ma) for the type stratum, which is overlain by the dinosaur-bearing Marília Formation, constraining the age of the Adamantina Formation at the site to late Coniacian–late Maastrichtian. This represents the first radioisotopic age for the Bauru Group, a key stratigraphic unit for the study of Cretaceous tetrapods in Gondwana.

The stem placental mammal Prokennalestes from the Early Cretaceous of Mongolia

All materials, including upper and lower jaw fragments and isolated teeth, of two closely related species of the stem placental mammal Prokennalestes, P. minor Kielan-Jaworowska et Dashzeveg, 1989 (258 specimens) and P. trofimovi Kielan-Jaworowska et Dashzeveg, 1989 (251 specimens), from the type locality of Khovoor (Early Cretaceous of Mongolia) are described. These extensive materials allow for the first time the study of morphological and size variability in an Early Cretaceous mammal. Prokennalestes can be diagnosed by the dental formula I?/4, C1/1, P4–5/5, M3/3, presence of the Meckelian groove, the mandibular foramen positioned dorsally on a prominent longitudinal ridge, presence of the masseteric foramen, double-rooted and premolariform lower canine, submolariform P5 with a large protocone and minute metacone, presence of the preparastyle, cusplike postmetacrista, and cusplike conules with incipient conular cristae on the upper molars, premolariform p5, the protoconid distinctly higher than the metaconid, the paraconid and metaconid connate at the base, transverse protocristid, and presence of distal metacristid on the lower molars. Two Prokennalestes species are reliably distinguished by the tooth dimensions (P. minor is smaller by 20%), the position of the infraorbital foramen (under P4 in P. minor and between P4 and P5 or under P5 in P. trofimovi), the presence of protoconal swelling on P4 (usually absent in P. minor and usually present in P. trofimovi), the ectocingulum extension in M3 (longer in P. minor), position of the posterior end of the mandibular symphysis (under p2 in P. minor, under p2–p3 in P. trofimovi), and by the position of the posterior mental foramen (under p4 in P. minor and under p5 in P. trofimovi). Taking into account considerable morphological differences between the two samples, they are regarded as different species rather than sexual morphs of the same species. Prokennalestes is a basal eutherian mammal similar in phylogenetic position to other stem placentals (Eomaia, Murtoilestes, Bobolestes, Aspanlestes). A more exact phylogenetic position of Prokennalestes can be established based on rigorous phylogenetic analysis including a large set of known stem therian and stem placental taxa.

Early cretaceous mammals from the Khamryn-Us and Shalan-Ikher localities in Mongolia.

New material of Early Cretaceous mammals from Mongolia, including dentary fragments of Gobiconodon borissiaki Trofimov, 1978 and G. hoburensis (Trofimov, 1978) from the well-known dinosaur locality Khamryn-Us (Dornogovi aimag) and a maxilla fragment of G. borissiaki from the new locality Shalan-Ikher (Övörkhangai aimag), is presented. The new data extend the knowledge on the morphology and intraspecific variability of Gobiconodon and the distribution of the Höovör Mammalian Assemblage in Mongolia.

A new mammal track from the Laramie Formation (Maastrichtian) at the Fossil Trace locality, Golden, Colorado

A previously unknown and morphologically distinct pentadactyl mammal track was recovered from the Upper Cretaceous (Maastrichtian) Laramie Formation at the Fossil Trace site, a National Natural Landmark which is the type locality for Schadipes crypticus, the only named mammal track known from North America. The track is different, and larger than S. crypticus, and thus is evidence of a diversity of mammal trackmakers at this site. Although Cretaceous mammal tracks are very rare, preliminary indications are that those currently known are all morphologically distinct and therefore indicative of a global diversity of different trackmakers, as the body fossil record suggests. Lack of well-preserved mammal trackways with morphologically distinct manus and pes footprints hampers efforts to name diagnostic ichnotaxa.

An enigmatic multituberculate mammal from the Early Cretaceous of Siberia, Russia

ABSTRACT Baidabatyr clivosus, gen. et sp. nov. (Multituberculata incertae sedis), is described on the basis of an ultimate upper premolar (P5) from the Lower Cretaceous Ilek Formation at Bol'shoi Kemchug 3 locality in Krasnoyarsk Territory, Russia. The new taxon differs from all known multituberculates by the cusp formula of the ultimate upper premolar (4:5:5), cusps well separated by valleys of flat crown surface, and three roots. It shares with a few non-cimolodontan multituberculates such rare characters of the ultimate upper premolar as elongated crown with length to width ratio of 2.0 and smooth enamel. Baidabatyr, gen. nov., is plesiomorphically similar to Paulchoffatiidae in having a horizontal profile of the ultimate upper premolar in lateral view. It likely represents a late survival of the Jurassic paulchoffatiid radiation of multitituberculates. Baidabatyr, gen. nov., is another relict taxon in the Early Cretaceous mammal fauna of the Ilek Formation, otherwise dominated by docodontans, eutriconodontans, and symmetrodontans. http://zoobank.org/urn:lsid:zoobank.org:pub:AD0FE7FA-8F78-4DFF-88DD-6F56545C6576 Citation for this article: Averianov, A., A. Lopatin, P. Skutschas, S. Ivantsov, E. Boitsova, and I. Kuzmin. 2017. An enigmatic multituberculate mammal from the Early Cretaceous of Siberia, Russia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1293070.

The mandible and dentition of the Early Cretaceous monotreme Teinolophos trusleri

Rich, T.H., Hopson, J.A., Gill, P.G., Trusler, P., Rogers-Davidson, S., Morton, S., Cifelli, R.L., Pickering, D., Kool, L., Siu, K., Burgmann, F.A., Senden, T., Evans, A.R., Wagstaff, B.E., Seegets-Villiers, D., Corfe, I.J., Flannery, T.F., Walker, K., Musser, A.M., Archer, M., Pian, R. & Vickers-Rich, P., June 2016. The mandible and dentition of the Early Cretaceous monotreme Teinolophos trusleri. Alcheringa 40, xx–xx. ISSN 0311-5518. The monotreme Teinolophos trusleri Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren, 1999 from the Early Cretaceous of Australia is redescribed and reinterpreted here in light of additional specimens of that species and compared with the exquisitely preserved Early Cretaceous mammals from Liaoning Province, China. Together, this material indicates that although T. trusleri lacked a rod of postdentary bones contacting the dentary, as occurs in non-mammalian cynodonts and basal mammaliaforms, it did not share the condition present in all living mammals, including monotremes, of having the three auditory ossicles, which directly connect the tympanic membrane to the fenestra ovalis, being freely suspended within the middle ear cavity. Rather, T. trusleri appears to have had an intermediate condition, present in some Early Cretaceous mammals from Liaoning, in which the postdentary bones cum ear ossicles retained a connection to a persisting Meckel’s cartilage although not to the dentary. Teinolophos thus indicates that the condition of freely suspended auditory ossicles was acquired independently in monotremes and therian mammals. Much of the anterior region of the lower jaw of Teinolophos is now known, along with an isolated upper ultimate premolar. The previously unknown anterior region of the jaw is elongated and delicate as in extant monotremes, but differs in having at least seven antemolar teeth, which are separated by distinct diastemata. The dental formula of the lower jaw of Teinolophos trusleri as now known is i2 c1 p4 m5. Both the deep lower jaw and the long-rooted upper premolar indicate that Teinolophos, unlike undoubted ornithorhynchids (including the extinct Obdurodon), lacked a bill. Thomas H. Rich [ trich@museum.vic.gov.au ], Sally Rogers-Davidson [ srogers@museum.vic.gov.au ], David Pickering [ dpick@museum.vic.gov.au ], Timothy F. Flannery [ tim.flannery@textpublishing.com.au ], Ken Walker [ kwalker@museum.vic.gov.au ], Museum Victoria, PO Box 666, Melbourne, Victoria 3001, Australia; James A. Hopson [ jhopson@uchicago.edu ], Department of Organismal Biology & Anatomy, University of Chicago,1025 East 57th Street, Chicago, IL 60637, USA; Pamela G. Gill [ pam.gill@bristol.ac.uk ], School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, U.K. and Earth Science Department, The Natural History Museum, Cromwell Road, London SW7 5BD, UK; Peter Trusler [ peter@petertrusler.com.au ], Lesley Kool [ koollesley@gmail.com ], Doris Seegets-Villiers [ doris.seegets-villiers@monash.edu ], Patricia Vickers-Rich [ pat.rich@monash.edu ], School of Earth, Atmosphere and Environment, Monash University, Victoria 3800, Australia; Steve Morton [ steve.morton@monash.edu ], Karen Siu [ karen.siu@monash.edu ], School of Physics and Astronomy, Monash University, Victoria 3800, Australia; Richard L. Cifelli [ rlc@ou.edu ] Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, Norman, OK 73072, USA; Flame A. Burgmann [ flame.burgmann@monash.edu ], Monash Centre for Electron Microscopy, 10 Innovation Walk, Monash University, Clayton, Victoria 3800, Australia; Tim Senden [ Tim.Senden@anu.edu.au ], Department of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia; Alistair R. Evans [ alistair.evans@monash.edu ], School of Biological Sciences, Monash University, Victoria 3800, Australia; Barbara E. Wagstaff [ wagstaff@unimelb.edu.au ], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Ian J. Corfe [ ian.corfe@helsinki.fi ], Institute of Biotechnology, Viikinkaari 9, 00014, University of Helsinki, Finland; Anne M. Musser [ anne.musser@austmus.gov.au ], Australian Museum, 1 College Street, Sydney NSW 2010 Australia; Michael Archer [ m.archer@unsw.edu.au ], School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia; Rebecca Pian [ rpian@amnh.org ], Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA. Received 7.4.2016; accepted 14.4.2016.

First mammal species identified from the Upper Cretaceous of the Rusca Montană Basin (Transylvania, Romania)

Multituberculate mammals are scarce in the Late Cretaceous of Europe, being recorded exclusively from the Maastrichtian terrestrial deposits of the Haţeg and Transylvanian basins, in Romania. Moreover, they all belong to the endemic and primitive cimolodontan family Kogaionidae. Here, we report multituberculate teeth originating from the Maastrichtian fluviatile sediments of the Rusca Montană Basin (Occidental Carpathians, Poiana Ruscă Mountains). This is the westernmost occurrence of these Cretaceous mammals in Romania. These teeth are assigned to Barbatodon oardaensis, the smallest Cretaceous kogaionid species. This study presents the first occurrence of this species outside the Metaliferi sedimentary area (southwestern Transylvania, Romania). The distribution of Romanian Maastrichtian kogaionids is also discussed.

The upper dentition and relationships of the enigmatic Australian Cretaceous mammal Kollikodon ritchiei

The upper dentition and relationships of the enigmatic Australian Cretaceous mammal Kollikodon ritchiei

Craniofacial Morphology of Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar

ABSTRACTThe Gondwanatheria are an enigmatic clade of Cretaceous and Paleogene mammals known from South America, Africa, Madagascar, India, and the Antarctic Peninsula. The eight valid species—each belonging to a monotypic genus and the first of which was described only 30 years ago—are represented almost exclusively by isolated teeth, in addition to fragmentary dentaries attributed to Sudamerica, Gondwanatherium, Ferugliotherium, and an unnamed taxon from Tanzania. No cranial (skull exclusive of lower jaw) or postcranial material has heretofore been assigned to the Gondwanatheria, a severe limitation that has precluded a comprehensive assessment of phylogenetic affinities. Here we describe, in detail, the first cranial specimen of a gondwanatherian mammal. This material consists of a complete and well-preserved cranium of the sudamericid Vintana sertichi, recovered from the Upper Cretaceous (Maastrichtian) Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. Salient features of the cranium include elongate, scimitar-like jugal flanges, huge orbits, strong klinorhynchy, and a vaulted nuchal region. Micro-computed tomography greatly facilitated the delineation of sutures and the description of internal morphology. The cranial features of Vintana are compared with those of a broad range of synapsids, with particular concentration on other Mesozoic mammaliaforms. The cranium of Vintana exhibits a mosaic of extremely primitive and extremely derived features. It is the second largest known for a Mesozoic mammaliaform, superseded only by that of the eutriconodontan Repenomamus giganticus from the Early Cretaceous of China. Vintana is the largest known Late Cretaceous mammaliaform; it is also the largest known Mesozoic mammaliaform from Gondwana.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP