How Did Alvarezsaurian Dinosaurs Evolve Monodactyl Hand?
Digit reduction occurs many times in tetrapod evolution, and the most famous example is the ‘horse series’ of North America. An international research team announced the discovery of two new Chinese dinosaurs: Bannykus and Xiyunykus, in the journal Current Biology, which shed light on how alvarezsaurian dinosaurs reduced and lost their fingers.
The new dinosaurs are based on two fossils collected by a joint research team led by XU Xing from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) of the Chinese Academy of Sciences. Xiynykus was discovered in 2005 in Zhunggar Basin, northwestern China, and Bannykuswas discovered a few years later in 2009 in western Inner Mongolia, north-central China.
Credit: Shi Aijuan
AT early times, unspecialized alvarezsaur fossils were the key to resolving this controversy, but until recently the group had at least a 90 million year gap in its fossil record, especially during the Early Cretaceous.
The new dinosaurs fall nearly at the midpoint of the 90-million year temporal gap between the earliest and latest alvarezsaurs. They contribute key phylogenetic and biogeographic information that firmly resolves Alvarezsauria as a monophyletic clade originating in Asia and dispersing to other continents.
Together, these observations document a major macroevolutionary shift from the plesiomorphic theropod condition of a relatively long arm and grasping hand in the earliest alvarezsaurs (e.g., Haplocheirus), to a long arm with a specialized hand in Bannykus and Xiyunykus, to the highly specialized short-limbed, functionally monodactyl hand in the latest evolving members of the clade.
This is a Alvarezsaurs restoration.
Credit: Vikto Radermacher
Dr. Roger Benson from the University of Oxford said, “The new fossils have long arms, showing that alvarezsaurs evolved short arms only later in their evoutionary history, in species with small body sizes. This is quite different to what happens in the classic example of tyrannosaurs, which have short arms and giant size.”
Contacts and sources:
Xu Xing
Chinese Academy of Sciences
Source: http://www.ineffableisland.com/2018/08/how-did-alvarezsaurian-dinosaurs-evolve.html
Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.
"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.
Please Help Support BeforeitsNews by trying our Natural Health Products below!
Order by Phone at 888-809-8385 or online at https://mitocopper.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomic.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomics.com M - F 9am to 5pm EST
Humic & Fulvic Trace Minerals Complex - Nature's most important supplement! Vivid Dreams again!
HNEX HydroNano EXtracellular Water - Improve immune system health and reduce inflammation.
Ultimate Clinical Potency Curcumin - Natural pain relief, reduce inflammation and so much more.
MitoCopper - Bioavailable Copper destroys pathogens and gives you more energy. (See Blood Video)
Oxy Powder - Natural Colon Cleanser! Cleans out toxic buildup with oxygen!
Nascent Iodine - Promotes detoxification, mental focus and thyroid health.
Smart Meter Cover - Reduces Smart Meter radiation by 96%! (See Video).
Evolution is a myth.