Mammal’s Nocturnal Shift after Dinosaur Extinction

The Evolution of Nocturnal and Diurnal Activities in Mammals

The majority of animals in the modern era, including diurnal species, exhibit sensory adjustments to nocturnal activities. It is believed to be the outcome of a protracted bottleneck that occurred during the early stages of mammalian evolution.

Patterns of Activity Dispersion

Over the course of a day, both mammal and plant species show distinctive patterns of activity dispersion (Maor et al. 1). People are able to anticipate the activities that take place at different times as environmental circumstances change and the length of day and night fluctuate. The behavioral and physiological adaptations, which are major drivers of species evolution, decide the outcome. Further, the shifts in the patterns of activity reveal the changes in abiotic and biotic conditions.

The Role of Eyes in Daytime Activities

Majority of mammals do not have a fovea, which is a region within the eyes of fish and reptiles allowing for increased visual acuity. In comparison to additional vertebrates, mammals have a difficulty to perceive color clearly in environments that are bright due to their reduced photoreceptors. Most of the mammals that are active in the day including carnivores and ungulates have a retinae that is rod-dominated. It is elaborated that their eyes are best suited for lower light frequencies referred to as night vision (Maor et al. 1). To enable the depreciated visual acuity of the mammals, they have an increased sensitivity of their olfactory and a broader hearing range frequency.

The Nocturnal Bottleneck

Walls in his study for the evolution of mammals to more activity during the day is attributed to the “nocturnal bottleneck.” He elaborates that the initial dominance of the adaptations of nocturnal activity in mammals resulted from the increased nocturnal evolution phase that currently characterizes how diverse mammals are in the current age (Maor et al. 1). The bottleneck explains that mammals had restrictions on activity by the interactions with the domination of dinosaurs in the Mesozoic period. The dinosaurs went extinct 62 million years ago together with the flying vertebrates and the study suggests that the extinction is what led to the appearance of diurnal and nocturnal mammals.

Evidence and Research Gaps

The support for the evolution hypothesis was drawn from morphological and anatomical studies inclusive of molecular studies but is still indirect and has a gap that requires more research. The ancient lifetime of dinosaurs is no longer a theory but a fact due to the archeological remains that have been discovered over time (Maor et al. 1). The study elaborates how mammals evolved over time and the space they obtained from the extinction of the harmful Mesozoic age was an essential aspect of their evolution.

Shift from Nocturnal to Diurnal Activities

The research outlines that the origin of mammals was probably from nocturnal and this ancestry was constant until the end of the Mesozoic approximately 10 million years ago. Mammals remained nocturnal throughout this period. The shift from the nocturnal occurred after the K-Pg to being diurnal. The bottleneck hypothesis was originated from the theory that the diurnal activity was attributed mostly to the extinction of dinosaurs (Maor et al. 1). The evidence on the development of cathermeral mammals does not provide concrete evidence to support their impact on the expansion of the niche occurring before the Mesozoic end. The significant decrease in the pressure brought about by the dinosaurs is the main characteristic attributed to the evolution of mammals to daytime activity. The coincidence is not only a theory but facts support it and hence is a solid hypothesis and result.

Analysis

Mammal distribution of their activities is mainly based on their nocturnality. The evolution of mammals to be species that operate during the day is highly attributed to nocturnal activity and the extinction of the Mesozoic age. A specific theory by researchers elaborates that mammals had a common ancestor that was nocturnal. However, current discoveries and research reveal the time when mammals began living during the day. The research provides information on the mammal species that had behavioral change first.

Impact of Extinction on Mammalian Behavioral Patterns

Dinosaurs were feared species in the past and not only mammals were afraid of them that other animals as well. Nature has different ways of taking a course at their extinction was a turning point of the behavioral patterns of mammals and other animals and plants included. However, the rule of the jungle elaborates that species have to adapt otherwise they die. Mammals had to evolve to be able to undertake activities during the day where there were high light frequencies in order for them to survive in nature.

Comparison: Journal vs Website

The journal in comparison to the viewer’s post not only have differentiation in the size of content but the journal provides greater depths of insight. It provides in the introduction an elaboration of the stages that led to the evolution of mammals and explains the characteristics of the environment at the time. The post on the website clearly elaborates the primates as the mammals that have been able to fully evolve to activity during the day. The posts in comparison to the journal additionally is more of reporting what the researchers concluded while the journal provides the detailed step by step activities that they undertook in their findings.

Work Cited

Maor, Roi et al. “Temporal Niche Expansion in Mammals from a Nocturnal Ancestor after Dinosaur Extinction.” Nature Ecology & Evolution (2017): n. pag. Web. 11 Nov. 2017.