Top fossil discoveries of 2019.

This was a turbulent year. The recent fires at Amazonas, Gran Canaria (Spain), Australia, and Indonesia sparked international outcry. Climate emergency movement took centre stage and Greta Thunberg become a household name as the face of the climate activism. Carl Sagan once said “You have to know the past to understand the present.”As the climate crisis escalates many studies published this year highlights the relation between mass extinctions and climate change.

Nevertheless, 2019 was another remarkable year for paleontology. Among the most striking fossil discoveries are China’s Qingjiang biota that document the Cambrian explosion; the nearly complete skull of Australopithecus anamensis, the oldest known species in a hominid genus that includes Australopithecus afarensis; and the world’s oldest fossilised forest found at an abandoned quarry in Cairo, New York. My top list (with a profound bias towards vertebrate paleontology) includes:

• Moros intrepidus

Moros intrepidus. Credit: Jorge Gonzalez

Moros intrepidus, a diminutive tyrannosauroid, from Cenomanian-aged terrestrial deposits of western North America. The holotype (NCSM 33392), preserves a partial right hind limb including portions of the femur, tibia, second and fourth metatarsals, and phalanges of the fourth pedal digit. According to the histological analysis, M. intrepidus exhibits a moderate growth rate, similar to Guanlong, a more primitive tyrannosauroid from the Late Jurassic of China. By contrast, large-bodied, tyrannosaurines from the last stages of the Cretaceous, like Gorgosaurus, were already triple their masses at similar ages. M. intrepidus suggests that North American tyrannosauroids were restricted to small sizes for a protracted period of ~15 million years and at some point at the Turonian, they embarked on a trend of rapid body size increases, to became the top predators of the Cretaceous.

• Bajadasaurus pronuspinax

Bajadasaurus pronuspinax gen. et sp. nov., from the Early Lower Cretaceous of Bajada Colorada Formation in Northern Patagonia, Argentina, was discovered in 2013, by a team of paleontologists from CONICET, Fundación Félix de Azara, Universidad Maimónides, and Museo Paleontológico Ernesto Bachmann. The holotype, MMCh-PV 75, includes a nearly complete skull (left maxilla, left lacrimal, both prefrontals, both frontals, both parietals, both postorbitals, both squamosals, left quadratojugal, both pterygoids, both quadrates, supraoccipital, exoccipital-opisthotic complex, basioccipital, basisphenoid, both prootics, both laterosphenoids, both orbitosphenoids, both dentaries, left surangular, both angulars, both splenials, left prearticular, left articular, isolated upper tooth row), both proatlases, atlantal neurapophyses, axis and the fifth cervical vertebra.

• Iberodactylus andreui

Comparison of the rostrum of Iberodactylus andreui gen. et sp. nov. (MPZ-2014/1) with a cast of a skull of Hamipterus tianshanensis. From Holgado et al., 2019)

Iberodactylus andreui is a pterosaurs from the Lower Cretaceous of Spain. The holotype (MPZ-2014/1) consists of the anterior portion of the rostrum (~198 mm in length), and includes a partially preserved premaxillary crest, and a fragment of the maxillary bone with several fragmentary teeth. The specimen preserved its original 3D shape, although exhibits frequent fractured bones, that added to the eroded bone surfaces, reveal an external thing layer of cortical bone of 1.5 mm. The robustness and height of the premaxillary crest, suggest that MPZ-2014/1 may represent a male specimen. The most striking feature of MPZ-2014/1 is the premaxillary crest. This crest exhibits well-developed elongated, sub-vertical striae and sulci, anteriorly curved, a combination that is quite similar to Hamipterus tianshanensis from the Berriasian-Albian of China.

• Suskityrannus hazelae

Partial skeleton of Suskityrannus hazelae. Image credit: Virginia Tech.

Suskityrannus hazelae is a small-bodied species phylogenetically intermediate between the oldest, smallest tyrannosauroids and the gigantic, last-surviving tyrannosaurids. The holotype specimen (MSM P4754) includes a partially articulated skull, and fragments of the braincase. The postcranial includes two cervical vertebrae with cervical rib fragments, , a trunk centrum, part of a sacral centrum, and distal portions of left metatarsals II–IV. The paratype (MSM P6178) includes the anterior portion of right dentary; left frontal, partial left postorbital, cervical, trunk, partial sacral and caudal vertebrae; isolated neural arches; partial left scapula; manual ungual fragments; partial pubes, femora, tibiae, fibulae and astragali; partial right pes; and bone fragments.

• Notatesseraeraptor frickensis

Notatesseraeraptor frickensis at the Sauriermuseum Frick.

Notatesseraeraptor frickensis, from the Late Triassic of Switzerland, is a basal member of Dilophosauridae, a clade that comprises Dilophosaurus, and Cryolophosaurus. The specimen belong to an immature individual of length 2.6–3.0 m, and it was collected in 2006 from Gruhalde clay pit in Frick (Aargau, Switzerland), a place well known for its abundant, articulated Plateosaurus material. The cranium is proportionally long and low as is commonly found in traditional coelophysoid-grade neotheropods. The postcranial skeleton includes two articulated forelimbs, 13 dorsal, four sacral and four proximal caudal vertebrae; cervical, dorsal and sacral ribs; chevrons; gastralia; and even stomach contents ( a well-preserved maxilla of the rhynchocephalian Clevosaurus).

• Ferrodraco lentoni

Ferrodraco lentoni gen. et sp. nov. holotype. From Pentland et al., Scientific Reports.

Ferrodraco lentoni, from the Winton Formation (Cenomanian–lower Turonian), is the most complete pterosaur specimen ever found in Australia. Discovered in 2017, the holotype specimen AODF 876 (Australian Age of Dinosaurs Fossil) includes a partial skull, five partial neck vertebrae, and bones from both the left and right wings. The wingspan of Ferrodraco was approximately 4 m, with a skull probably reaching 60 cm in length. The generic name comes from the Latin language: ferrum (iron), in reference to the ironstone preservation of the holotype specimen, and draco (dragon). The species name, lentoni, honours former Winton Shire mayor Graham Thomas ‘Butch’ Lenton. Based on several cranial synapomorphies, including the presence of a mandibular groove, smooth and blade-like premaxillary and mandibular crests, and spike-shaped teeth, Ferrodraco falls within the clade Anhangueria. This group has also been recorded in the Early Cretaceous of Brazil, China and England.

• Adratiklit boulahfa

Isolated cervical vertebra referred to Adratiklit boulahfa. From Maidment et al., 2019.

Adratiklit boulahfa, from the Middle Jurassic of Morocco, is the oldest stegosaur ever found. The holotype (NHMUK PV R37366) of Adratiklit boulahfa is a dorsal vertebra. Referred specimens include three cervical vertebrae (NHMUK PV R37367 and NHMUK R37368, the latter specimen consisting of a series of two articulated bones), a dorsal vertebra (NHMUK PV R37365) and a left humerus (NHMUK PV R37007). Stegosauria is a clade of ornithischian dinosaurs and the closest relative to Ankylosauria; together they form the Eurypoda. These armored dinosaurs were diverse and abundant throughout the Late Jurassic and Cretaceous in Laurasia; but their remains are extremely rare in Gondwana. It has been suggested that Isaberrysaura mollensis from the Jurassic of Argentina might be a stegosaur. Additionally fragmentary discoveries of possible eurypodans have been made in Australia, New Zealand, India and Madagascar, while some eurypodan trackways have been identified in Morocco, Bolivia and Brazil.

• Gnathovorax cabreirai.

Skull of Gnathovorax cabreirai. From Pacheco et al., 2019

Gnathovorax cabreirai was found in 2014 at the Marchezan site, municipality of São João do Polêsine, Rio Grande do Sul, Brazil. The generic name means “jaws inclined to devour”. The specific name honors Dr. Sérgio Furtado Cabreira, the palaeontologist that found the specimen. The Santa Maria Formation in southern Brazil, comprises a succession of Middle to Late Triassic sedimentary rocks that have been long renowned for their rich tetrapod fossils including one of the oldest (and the best preserved) associations of dinosaur and dinosaur precursor. Gnathovorax lived around 230 million years ago and measured about three meters in length. The holotype (CAPPA/UFSM 0009) is an almost complete and partially articulated skeleton. The skull is almost entirely preserved. Among other characters, Gnathovorax presents three premaxillary teeth; an additonal fenestra between the maxilla and premaxilla contact; two well defined laminae in the antorbital fossa of the maxilla, with a depression between them. The proximal portion of the femur lacks a caudomedial tuber. The tibia equals 90% of the femoral length and there are three phalanges in pedal digit V.

• Asfaltovenator vialidadi.

Skeletal reconstruction and postcranial anatomy of Asfaltovenator vialidadi, MPEF PV 3440. From Rauhut and Pol, 2019.

Asfaltovenator vialidadi, a new basal tetanuran from the Middle Jurassic of Argentina, shed new ligth on the early radiation of this group. The holotype (MPEF PV 3440) includes an almost complete skull and a partial skeleton. The skull is high and slightly arched, similar to that of other allosauroids and reached 75–80 cm long. The estimated body length of the holotype is 7–8 m, which makes Asfaltovenator comparable in size to the well-known Allosaurus. The phylogenetic analysis of A. vialidadi suggest that Allosauroidea  and Megalosauroidea have a common ancestor that they do not share with coelurosaurs. The new study also suggest that the Pliensbachian-Toarcian extinction event was a potential driver of tetanuran radiation.

• A postcard from the Cretaceous

Nullotitan glaciaris gen. et sp. nov. Cervical vertebra (MACN Pv 18644) in left lateral (A), dorsal (B), posterior (C), right lateral (D), and longitudinal section (E) views

The Chorrillo Formation ((Upper Cretaceous) in the southern region of the Argentine Patagonia yielded an extraordinare fossil assemblage. Plants, palynomorphs, invertebrates and vertebrates constitutes an amazing window into de Cretaceous. Dinosaur remains include the elasmarian (basal Iguanodontia) Isasicursor santacrucensis gen. et sp. nov; the large titanosaur Nullotitan glaciaris gen. et sp. nov., small Megaraptoridae indet., and fragments of sauropod and theropod eggshells.

References:

Zanno, L.E, Tucker, R.T., Canoville, A., Avrahami, H.M., Gates, T.A., Makovicky, P.J. (2019), Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record, Communications Biology, DOI: 10.1038/s42003-019-0308-7

Gallina, Pablo A., Apesteguía, Sebastián, Canale, Juan I., Haluza, Alejandro (2019), A new long-spined dinosaur from Patagonia sheds light on sauropod defense system, Scientific Reports volume 9, Article number: 1392 DOI: https://doi.org/10.1038/s41598-018-37943-3

Borja Holgado, Rodrigo V. Pêgas, José Ignacio Canudo, Josep Fortuny, Taissa Rodrigues, Julio Company & Alexander W.A. Kellner, 2019, “On a new crested pterodactyloid from the Early Cretaceous of the Iberian Peninsula and the radiation of the clade Anhangueria”, Scientific Reports 9: 4940

Sterling J. Nesbitt et al. A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology & Evolution, published online May 6, 2019; doi: 10.1038/s41559-019-0888-0

Marion Zahner; Winand Brinkmann (2019). “A Triassic averostran-line theropod from Switzerland and the early evolution of dinosaurs”. Nature Ecology & Evolution. doi:10.1038/s41559-019-0941-z

Adele H. Pentland et al., Ferrodraco lentoni gen. et sp. nov., a new ornithocheirid pterosaur from the Winton formation (cenomanian-lower turonian) of Queensland, Australia, DOI: 10.1038/s41598-019-49789-4

Maidment, Susannah C. R.; Raven, Thomas J.; Ouarhache, Driss; Barrett, Paul M. (2019-08-16). “North Africa’s first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity”. Gondwana Research. 77: 82–97. doi:10.1016/j.gr.2019.07.007
Pacheco C, Müller RT, Langer M, Pretto FA, Kerber L, Dias da Silva S. 2019. Gnathovorax cabreirai: a new early dinosaur and the origin and initial radiation of predatory dinosaurs. PeerJ 7:e7963 https://doi.org/10.7717/peerj.7963

Rauhut, Oliver W. M.; Pol, Diego (2019), Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs https://www.nature.com/articles/s41598-019-53672-7
Novas, F., Agnolin, F., Rozadilla, S., Aranciaga-Rolando, A., Brissón-Eli, F., Motta, M., Cerroni, M., Ezcurra, M., Martinelli, A., D’Angelo, J., Álvarez-Herrera, G., Gentil, A., Bogan, S., Chimento, N., García-Marsà, J., Lo Coco, G., Miquel, S., Brito, F., Vera, E., Loinaze, V., Fernandez, M., & Salgado, L. (2019). Paleontological discoveries in the Chorrillo Formation (upper Campanian-lower Maastrichtian, Upper Cretaceous), Santa Cruz Province, Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales, 21(2), 217-293.