F. A. Gianechini, J. G. Meso, A. H. Méndez, A. C. Garrido & L. S. Filippi (2024)
A new maniraptoran femur with alvarezsaurian affinities from the Plottier Formation (Coniacian-Santonian), northern Patagonia
HIstorical Biology (advance online publication)
doi:
https://doi.org/10.1080/08912963.2024.2414206 https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2414206A new specimen, MAU-Pv-PH-453, comprising an isolated femur from the Plottier Formation (Coniacian-Santonian), northern Patagonia, is described here. Its characteristics, i.e., an anteriorly curved diaphysis; fused lesser and greater trochanters forming a trochanteric crest; a prominent medially directed head; and the absence of a fourth trochanter, allow us to identify it as belonging to a maniraptoran theropod. Among Patagonian maniraptorans, MAU-Pv-PH-453 shares similarities with alvarezsaurians, such as the absence of a posterior trochanter, a trochanteric shelf, and the fourth trochanter. However, in Patagonian alvarezsaurs, the lesser and greater trochanters are generally separated by a cleft. Notably, MAU-Pv-PH-453 exhibits some features seen in femora of parvicursorine alvarezsaurids, including a proximally projected trochanteric crest and an L-shaped profile in proximal view. However, MAU-Pv-PH-453 presents differences with parvicursorines, such as a knob partially separating the lesser and greater trochanters. Phylogenetically, MAU-Pv-PH-453 may have parvicursorine affinities, although its fragmentary nature might generate a bias in its phylogenetic position. Due to the lack of more diagnostic characters, MAU-Pv-PH-453 is assigned to Alvarezsauria indet. This material represents the second theropod record from the Plottier Formation and it could fill a temporal gap (between Coniacian and Santonian) in the record of Upper Cretaceous Patagonian alvarezsaurians.
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Han Sang Yoon, Yuong-Nam Lee, Euijun Park & Sungjin Lee (2024)
A small sauropod trackway from the Upper Cretaceous Jindong Formation (Cenomanian), Goseong County, South Korea
Cretaceous Research 106022
doi:
https://doi.org/10.1016/j.cretres.2024.106022https://www.sciencedirect.com/science/article/abs/pii/S0195667124001952Highlights
Discovery of one of the smallest sauropod trackways from the Late Cretaceous of Korea.
The trackmaker was interpreted as an early juvenile titanosauriform sauropod (an approximate body length of 2.3 meters).
It is a notable example illustrating early juvenile sauropod locomotion, moving at a speed slower than 2 km/h in a trotting gait.
The sauropod trackways in the Jindong Formation (Cenomanian) show a negative correlation between trackmaker size and trackway gauge.
Abstract
In 2000, a small sauropod trackway was discovered in the Upper Cretaceous Jindong Formation (Cenomanian) at Eosin-ri, Goseong County, South Korea. This quadrupedal trackway consists of 34 very small sauropod footprints, with an average manus width of 10.0 cm and pes length of 12.8 cm, showing low heteropody (mean IPS/IMS: 1.38). The manus tracks are oval to kidney-shaped, while the pes tracks are generally subcircular to V-shaped, lacking distinct claw marks. The trackway shows a medium to wide gauge (mean PTR: 38.8%; WAP/PL: 1.18). The small footprint size and estimated trackmaker body size suggest that the trackmaker was an early juvenile titanosauriform sauropod based on the contemporaneous sauropod taxa of East Asia. Sauropod trackways reported from the Jindong Formation, including the Eosin-ri trackway, exhibit a tendency for narrower trackway gauges as pes length increases. This negative correlation between trackmaker size and trackway gauge may imply ontogenetic or behavioral variations within the same clade of sauropods or differences in gait or body plan amongst different sauropod taxa.
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