In this article we are going to address the topic of Juramaia and explore its different facets. Juramaia is a topic of great relevance in today's society, since it impacts various aspects of daily life. Throughout this article we will analyze its origin, its evolution over time and its influence in different areas. In addition, we will examine the different perspectives that exist around Juramaia, with the aim of offering a complete and enriching vision on this topic. Through a multidimensional approach, we aim to offer our readers a broad and detailed vision of Juramaia, with the purpose of encouraging reflection and debate around this topic that is so relevant today.
Juramaia Temporal range: ?
| |
---|---|
Restoration | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Subclass: | Theria |
Genus: | †Juramaia Luo et al., 2011 |
Species | |
Juramaia is an extinct genus of a therian mammal, possibly a very basal eutherian mammal, known from the Late Jurassic (Oxfordian stage) or Early Cretaceous deposits of western Liaoning, China. It is a small shrew-like mammal measuring about 10 cm (3.9 in) long and weighing around 15–25 g (0.53–0.88 oz), making it similar in size to the modern De Winton's shrew.
Juramaia is known from the holotype BMNH PM1343, an articulated and nearly complete skeleton including incomplete skull preserved with full dentition. It was collected in the Daxigou site, Jianchang, from the Tiaojishan Formation dated at about 160 million years ago. It was first named by Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji in 2011 and the type species is Juramaia sinensis.
The discovery of Juramaia provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the marsupials 35 million years earlier than previously thought. Furthermore, its discovery fills gaps in the fossil record and helps to calibrate modern, DNA-based methods of dating the evolution. Based on climbing adaptations found in the forelimb bones, it has been suggested that the basal stock of Eutheria was arboreal, in a manner resembling that of modern rats.
| |||||||||||||||||||||||||
However, Sweetman et al. (2017) considered Juramaia as a stem therian instead, and the Late Jurassic dating has been questioned, with King et al. (2020) suggesting that Juramaia may originate from Early Cretaceous based on tip-dating analyses, which would make it contemporaneous to several other known eutherians.