Recent non-dino papers with free pdfs:
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Newly described specimens of North American Eocene turtles provide valuable information on their morphology and, more specifically, variation, both intraspecific and ontogenetic. We describe several complete and nearly complete testudinoid (Testudinoidea) specimens, including juvenile specimens of Hadrianus corsoni, H. majusculus, Echmatemys haydeni and E. naomi. These specimens help us determine that the oldest and most basal tortoises are from the western United States, suggesting Testudinidae evolved in North America from one of the geoemydid-like forms in the genus Echmatemys, which have their lowest stratigraphic occurrence in the earliest Wasatchian North American land-mammal âageâ (early Eocene, Ypresian, ~53 Ma).
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Lizards run quickly and stably in a bipedal gait, with their bodies exhibiting a lateral S-shaped undulation. We investigate the relationship between a lizard's bipedal running and its body movement with the help of a dynamic simulation. In this study, a dynamic theoretical model of lizard is assumed as a three-link consisting of an anterior and posterior bodies, and a tail, with morphometrics based on Callisaurus draconoides. When a lizard runs straight in a stable bipedal gait, its pelvic rotation is periodically synchronized with its gait. This study shows that the S-shaped body undulation with the yaw motion is generated by minimizing the square of joint torque. Furthermore, we performed the biomechanical simulation to figure out the relationship between the lizard's lateral body undulation and the bipedal running locomotion. In the biomechanical simulation, all joint torques significantly vary by the waist and tail' motions at the same locomotion. Besides, when the waist and tail joint angles increase, the stride length and duration of the model also increase, and the stride frequency decreases at the same running speed. It means that the lizard's undulatory body movements increase its stride and help it run faster. In this study, we found the benefits of the lizard's undulatory body movement and figured out the relationship between the body movement and the locomotion by analyzing the dynamics. In the future works, we will analyze body movements under different environments with various simulators.
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Association of two subadult and one adult Smilodon fatalis from Ecuador
Rare, likely genetic condition suggests subadults are siblings
S. fatalis appears to have exhibited fast growth over a prolonged period
Comparison with growth in lions and tigers suggests a unique growth strategy
Summary
The saber-toothed cat Smilodon fatalis is known predominantly from âpredator trapâ deposits, which has made many aspects of its life history difficult to infer. Here, we describe an association of at least two subadult and one adult S. fatalis from Pleistocene coastal deposits in Ecuador. The assemblage likely derived from a catastrophic mass mortality event, and thereby provides insights into the behavior of the species. The presence of a P3 in the subadult dentaries suggests inheritance, a rare instance of familial relatedness in the fossil record. The siblings were at least two years old and were associated with an adult that was likely their mother, indicating prolonged parental care in S. fatalis. Comparison with the growth of pantherine cats suggests that S. fatalis had a unique growth strategy among big cats that combines a growth rate that is similar to a tiger and the extended growth period of a lion.
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