Paleontologist Publications

For one article, she is part of an international team of paleontologists who just published the description of a remarkable new species of horned dinosaur in PeerJ. The description of Lokiceratops rangiformis is based on a skull and partial skeleton that were unearthed in Kennedy Coulee in northern Montana along the USA-Canada border. The creature is distinguished by a number of unique features including the lack of a nose horn, along with the number, pattern, and shapes of the horns along the edge of the frill. The name Lokiceratops translates as “Loki’s horned face” honoring the Norse god Loki, while rangiformis refers to the differing horn lengths on each side of the frill, similar to the asymmetric horns in caribou. The skull is longer than that of any other dinosaur within its group, Centrosaurinae, approaching the size of later horned giants. It is the largest centrosaur ever found in North America, and was the most massive herbivore in its ecosystem. At 78 million years old, Lokiceratops rangiformis is one of the geologically-oldest species of horned dinosaurs in the northern USA and Canada, appearing at least 12 million years earlier than Triceratops. Excavated by a commercial fossil dealer, the specimen was sold to the Museum of Evolution in Maribo, Denmark, where its skull has been on display for more than a year (photo at right), while the species description was underway. Not surprisingly, the news coverage has been fairly robust, with coverage in New York Times, ABC News, CNN, BBC Wildlife, Discover, and more. Jingmai is also a co-author on a new article in Science Bulletin that sheds new light on the evolution of the mammalian neck, written with  colleagues from University of Potsdam (Germany), Polish Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology (Beijing), and University of Chicago. The typical mammalian neck, consisting of seven cervical vertebrae (C1–C7), was established in the cynodont forerunners of modern mammals by the Late Permian. This structure is precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the lineage including crown placental mammals, has a fossil record extending back more than 125 million years, and evidences significant morphological diversification in the Mesozoic. However, very little is known about the early evolution of the eutherian neck, and its functional adaptations. The team analyzed a specimen of Zalambdalestes lechei—a shrew-like mammal from the Late Cretaceous of Mongolia—which boasts exceptional preservation of an almost complete series of cervical vertebrae (C2–C7) revealing a highly modified axis (C2). The team explored the significance of this cervical morphology by integrating comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. They compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of eutherian neck morphology, and suggest that Zalambdalestes had a feeding behavior similar to insectivores specialized in worm-eating, and defensive behaviors in akin to modern spiniferous mammals (e.g., porcupines, echidnas).
June 21. 2024