Here, Wang and his team report and explain a new types of Miocene giraffoid, Discokeryx xiezhi. The fossils, dated to roughly 17 million years back, show that this ancient giraffoid species had helmet-like headgear and especially complicated head and neck joints.
The fossil community in the Junggar Basin at ~ 17 million years earlier. Discokeryx xiezhi are in the middle. Credit: Guo Xiaocong
According to the scientists, these strange morphological qualities reveal an adaption for fierce head-butting habits. In truth, the authors recommend that Discokeryx xiezhi might have possessed the most optimized head-butting head and neck adaptation yet determined in vertebrate evolution.
Additionally, tooth enamel isotope data from these fossils suggest that the types likewise most likely filled a particular environmental specific niche in the environment unavailable to other modern herbivores. In overall, the researchers suggest that early giraffoid evolution is more complex than formerly understood, where, in addition to competition for food, sexual battle likely played a crucial role in shaping the groups long and uniquely adjusted necks.
Reference: “Sexual choice promotes giraffoid head-neck development and eco-friendly adaptation” by Shi-Qi Wang, Jie Ye, Jin Meng, Chunxiao Li, Loïc Costeur, Bastien Mennecart, Chi Zhang, Ji Zhang, Manuela Aiglstorfer, Yang Wang, Yan Wu, Wen-Yu Wu and Tao Deng, 3 June 2022, Science.DOI: 10.1126/ science.abl8316.
Intermale-competitions of giraffoid, foreground: Discokeryx xiezhi, background: Giraffa camelopardalis. Credit: Wang Yu and Guo Xiaocong
Fossils demonstrate that head-bashing fight added to the development of the long necks of giraffes.
The authors of the study propose an alternative theory for the origin of the long necks of modern giraffes: giraffes needed them for head-bashing combat they utilized in competition for mates. This theory is supported by an analysis of an early giraffe ancestors unique head and neck fossils, which include disk-shaped helmet-like headgear and extremely complex head-neck joints.
Because Charles Darwin originally proposed the concepts of adaptive evolution and natural choice, the distinctively long neck of the contemporary giraffe– the tallest land animal and largest ruminant in the world– has long been viewed as an essential example of these procedures. According to common belief, food rivalry resulted in neck elongation, which allowed giraffes to forage for treetop leaves in the African Savannah woodlands much beyond the reach of other ruminant species.
Modeling of high-speed head-butting in Discokeryx xiezhi utilizing finite component analyses, with (A) and without (B) the complicated joints in between cranium and vertebrae, showing the stable (A) or over-bending (B) head-neck articulation. Credit: IVPP
Others, however, have actually put forward the “necks-for-sex” theory, which competes that intermale competition-driven sexual selection might likewise have had a function in the development of the extended neck. Shi-Qi Wang and coworkers declare that remains of extinct giraffe types can shed light on these evolutionary systems.
