Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America

Predator-prey interactions revealed by vertebrate trace fossils are extremely rare. We present footprint evidence from White Sands National Monument in New Mexico for the association of sloth and human trackways. Geologically, the sloth and human trackways were made contemporaneously, and the sloth trackways show evidence of evasion and defensive behavior when associated with human tracks. Behavioral inferences from these trackways indicate prey selection and suggest that humans were harassing, stalking, and/or hunting the now-extinct giant ground sloth in the terminal Pleistocene

Redesign Your Writing & Research Assignments

With so many variables to account for in the fall, the writing and research assignments we designed for a 14-week semester with regular in-person access to campus resources may no longer be realistic or effective. Join Melissa Forbes, Director of the Writing Center and First-Year Writing, and Research & Instruction Librarians Kerri Odess-Harnish and Meggan Smith for tips on redesigning writing and research assignments to help students succeed whatever the semester looks like. A short 10-minute presentation will be followed by Q&A and open discussion

Symbolic analysis of analog circuits containing voltage mirrors

7 páginas, 7 figuras, 2 tablas, 4 imágenes.-- Open Access: This article is distributed under the terms of the Creative Commons Attribution Noncommercial License.The pathological elements voltage mirror (VM) and current mirror (CM) have shown advantages in analog behavioral modeling and circuit synthesis, where many nullor-mirror equivalences have been explored to design and to transform voltage-mode circuits to current-mode ones and viceversa. However, both the VM and CM have not equivalents to perform automatic symbolic circuit analysis. In this manner, we introduce nullor-equivalents for these pathological elements allowing to include parasitics and to perform only symbolic nodal analysis. The nullor-equivalent of the CM is extended to provide multiple-outpus (MO-CM). Finally, two active filters containing VMs, CMs and MO-CMs are analysed to show the usefulness of the models.This work is supported by: UC-MEXUS and CONACyT under grants CN-09-310 and 48396-Y; by Promep-Mexico under grant UATLX-PTC-088; by Consejeria de Innovacion, Ciencia y Empresa, Junta de Andalucia-Spain TIC-2532; and by the JAE-Doc program of CSIC co-funded by FSE, Spain.Peer reviewe

Walking in mud: Remarkable Pleistocene human trackways from White Sands National Park (New Mexico)

Human tracks at White Sands National Park record more than one and a half kilometres of an out‐ and‐back journey and form the longest Late Pleistocene‐age double human trackway in the world. An adolescent or small adult female made two trips separated by at least several hours, carrying a young child in at least one direction. Despite giant ground sloth and Columbian Mammoth transecting them between the outbound and return journeys, the human tracks show no changes indicative of predator/prey awareness. In contrast, the giant ground sloth tracks show behaviour consistent with human predator awareness, while mammoth tracks show no such apparent concern. The human footprints are morphologically variable and exhibit left‐right asymmetry, which might be due to child carrying. We explore this morphological variability using methods based on the analysis of objective track outlines, which add to the analytical toolkit available for use at other human footprint sites. The sheer number of tracks and their remarkable morphological variability have implications for the reliability of inferences made using much smaller samples as are more common at typical footprint sites. One conclusion is that the number of footprints required to make reliable biometric inferences is larger than often assumed

The ichnology of White Sands (New Mexico): Linear traces and human footprints, evidence of transport technology?

A travois is crafted from one or more wooden poles and is one of the simplest prehistoric vehicles. Although these devices likely played vital roles in the lives of ancient peoples, they have low preservation potential in the archaeological record. Here we report linear features associated with human footprints, some of which are dated to ∼22,000 years old, preserved in fine-grained sediments at White Sands National Park (New Mexico, USA). Using a range of examples, we identify three morphological types of trace in late Pleistocene sediments. Type I features occur as single, or bifurcating, narrow (depth > width) grooves which extend in planform from 2 to 50 m in length and trace either straight, gently curved or more irregular lines. They are associated with human footprints, which are truncated longitudinally by the groove and are not associated with other animal tracks. Type II examples are broader (width > depth) and form shallow runnels that typically have straight planforms and may truncate human footprints to one side. Type III examples consist of two parallel, equidistant grooves between 250 and 350 mm apart. They trace gently curving lines that can extend for 30+ m. Human footprints are associated with these features and may occur between, and to the side of, the parallel grooves. We review a range of possible interpretations including both human and non-human explanations and conclude that the most parsimonious explanation is that they represent drag marks formed by travois consisting of a single pole or crossed poles pulled by humans, presumably during the transport of resources. As such this unique footprint record may represent one of the earliest pieces of evidence for the use of transport technology

Independent age estimates resolve the controversy of ancient human footprints at White Sands

Human footprints at White Sands National Park, New Mexico, USA, reportedly date to between ~23,000 and 21,000 years ago according to radiocarbon dating of seeds from the aquatic plant Ruppia cirrhosa. These ages remain controversial because of potential old carbon reservoir effects that could compromise their accuracy. We present new calibrated 14C ages of terrestrial pollen collected from the same stratigraphic horizons as those of the Ruppia seeds, along with optically stimulated luminescence ages of sediments from within the human footprint–bearing sequence, to evaluate the veracity of the seed ages. The results show that the chronologic framework originally established for the White Sands footprints is robust and reaffirm that humans were present in North America during the Last Glacial Maximum

Walking in mud: Remarkable Pleistocene human trackways from White Sands National Park (New Mexico)

Human tracks at White Sands National Park record more than one and a half kilometres of an out- and-return journey and form the longest Late Pleistocene-age double human trackway in the world. An adolescent or small adult female made two trips separated by at least several hours, carrying a young child in at least one direction. Despite giant ground sloth and Columbian Mammoth transecting them between the outbound and return journeys, the human tracks show no changes indicative of predator/prey awareness. In contrast, the giant ground sloth tracks show behaviour consistent with human predator awareness, while mammoth tracks show no such apparent concern. The human footprints are morphologically variable and exhibit left-right asymmetry, which might be due to child carrying. We explore this morphological variability using methods based on the analysis of objective track outlines, which add to the analytical toolkit available for use at other human footprint sites. The sheer number of tracks and their remarkable morphological variability have implications for the reliability of inferences made using much smaller samples as are more common at typical footprint sites. One conclusion is that the number of footprints required to make reliable biometric inferences is greater than often assumed

Evidence of humans in North America during the Last Glacial Maximum.

Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. Questions remain about when and how people migrated, where they originated, and how their arrival affected the established fauna and landscape. Here, we present evidence from excavated surfaces in White Sands National Park (New Mexico, United States), where multiple in situ human footprints are stratigraphically constrained and bracketed by seed layers that yield calibrated radiocarbon ages between ~23 and 21 thousand years ago. These findings confirm the presence of humans in North America during the Last Glacial Maximum, adding evidence to the antiquity of human colonization of the Americas and providing a temporal range extension for the coexistence of early inhabitants and Pleistocene megafauna