(Press-News.org) How did the ankylosaur get its tail club? According to research from North Carolina State University and the North Carolina Museum of Natural Sciences that traces the evolution of the ankylosaur's distinctive tail, the handle arrived first on the scene, and the knot at the end of the tail followed.
The typical ankylosaur had a wide armored body and a flexible tail. But one group of ankylosaurs - ankylosaurids - also had a tail club that could have served as a useful weapon. These "weaponized" ankylosaurids lived about 66 million years ago, during the Cretaceous period. But ankylosaurian dinosaurs were around well before that time - over 145 million years ago, during the Jurassic.
Victoria Arbour, a postdoctoral researcher at NC State and the North Carolina Museum of Natural Sciences, was a Ph.D. candidate at the University of Alberta when she began studying how the ankylosaur developed its unique tail. In a paper published in the Journal of Anatomy, Arbour compared Jurassic ankylosaur specimens to those from the early and late Cretaceous period, tracing the tail's evolution from flexible to fearsome.
An ankylosaur's tail is composed of a handle and a knob. The knob is made up of osteoderms, a special kind of bone formed in the skin that's unique to armored dinosaurs. The handle is the lower portion of the tail which supports the knob.
"In order for an ankylosaur to be able to support the weight of a knob and swing it effectively, the tail needs to be stiff, like an ax handle," says Arbour. "For that to occur, the vertebrae along the tail had to become less flexible, otherwise the momentum generated by the knob's weight could tear muscle or dislocate vertebrae."
Arbour looked at a number of early ankylosaurids including: Liaoningosaurus which lived 122 million years ago; Gobisaurus, which lived 90 million years ago; and Pinacosaurus, which lived 75 million years ago and is the earliest specimen with a complete tail club, to determine which of three possible evolutionary paths was most likely.
"There are three ways the tail could have evolved," Arbour says. "The knob could have evolved first, in which case you'd see ankylosaurids with osteoderms enveloping the end of the tail, but with the tail remaining flexible. The handle could have evolved first, meaning you would see early ankylosaurids with overlapping or fused tail vertebrae. Or the knob and handle could have evolved in tandem, in which case you'd see ankylosaurids with both structures, but there could have been other differences like shorter handles or smaller knobs."
By comparing the tails of the specimens, Arbour saw that by the early Cretaceous, ankylosaurs had begun to develop stiff tails with fused vertebrae. The knob appeared in the late Cretaceous.
"While it's possible that some of the species could still have developed the handle and knob in tandem, it seems most likely that the tail stiffened prior to the growth of the osteoderm knob, in order to maximize the tail's effectiveness as a weapon," Arbour says.
INFORMATION:
Philip Currie, professor and research chair in dinosaur paleobiology at the University of Alberta, Canada, contributed to the work. The research was funded by the National Sciences and Engineering Research Council, the Killam Trusts, and the Dinosaur Research Institute.
Note to editors: The paper's abstract follows.
"Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features"
Authors: Victoria Arbour, NC State University, North Carolina Museum of Natural Sciences, and the University of Alberta, Canada; Philip Currie, University of Alberta, Canada
Published: Journal of Anatomy
DOI: 10.1111/joa.12363
Abstract: Ankylosaurid ankylosaurs were quadrupedal, herbivorous dinosaurs with abundant dermal ossifications. They are best known for their distinctive tail club composed of stiff, interlocking vertebrae (the handle) and large, bulbous osteoderms (the knob), which may have been used as a weapon. However, tail clubs appear relatively late in the evolution of ankylosaurids, and seemed to have been present only in a derived clade of ankylosaurids during the last 20 million years of the Mesozoic Era. New evidence from mid Cretaceous fossils from China suggests that the evolution of the tail club occurred at least 40 million years earlier, and in a stepwise manner, with early ankylosaurids evolving handle-like vertebrae before the distal osteoderms enlarged and coossified to form a knob.
LONDON (Aug. 31, 2015) -- Cardiologists failed to identify more than half of basic and about 35 percent of advanced pre-recorded murmurs, but skills improved after a 90 minute training session, according to research presented today at the European Society of Cardiology Congress 2015.
Recent breakthroughs in the transcatheter treatment of aortic and mitral valve disorders provide new therapies for patients, but physicians must be able to detect valve problems in a timely manner for patients to see the full benefit of these advances, said Michael Barrett, MD, the lead ...
London, UK - 31 Aug 2015: A gene associated with sudden cardiac death in the general population has been identified using implantable cardioverter defibrillator (ICD) monitoring in research presented for the first time at ESC Congress today.1 The research included patients from the DISCOVERY trial and Oregon-SUDS and discovered that a polymorphism in the GNAS gene predicted ventricular tachyarrhythmias and sudden cardiac death.
"This is the first time a gene has been identified using ICD monitoring and then confirmed to be associated with sudden cardiac death in the general ...
LONDON, UK - 30 August, 2015: In patients with type 2 diabetes and acute coronary syndrome, the glucose-lowering medication lixisenatide did not increase or decrease the rate of cardiovascular (CV) events compared to placebo, according to results of the Evaluation of Lixisenatide in Acute Coronary Syndrome (ELIXA) trial.
The study, presented today at ESC Congress 2015, "demonstrates the cardiovascular safety of lixisenatide", reported Eldrin F. Lewis, MD, MPH, a member of the ELIXA trial's executive committee, a physician in the Cardiovascular Medicine Division at Brigham ...
LONDON, UK - 30 August, 2015: Patients with type-2 diabetes and cardiovascular disease can safely take the antihyperglycemic drug sitagliptin without an increased risk of cardiovascular complications - even if they have a history of heart failure - a new analysis of the TECOS (Trial Evaluating Cardiovascular Outcomes with Sitagliptin) study shows.
The findings, presented today at ESC Congress 2015, "provide reassurance to patients and prescribers about the cardiovascular safety of sitagliptin" - a dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin - according to Paul ...
London, UK - 31 Aug 2015: Depressed patients have more frequent chest pain even in the absence of coronary artery disease, according to results from the Emory Cardiovascular Biobank presented at ESC Congress today by Dr Salim Hayek, a cardiologist at Emory University School of Medicine in Atlanta, Georgia, US.1 The findings suggest that pain and depression may share a common neurochemical pathway.
"Depression is a common and well recognised risk factor for the development of heart disease," said Dr Hayek. "Patients with known heart disease and depression tend to experience ...
London, UK - 31 Aug 2015: Retrieval of larger thrombi during intra arterial treatment (IAT) is associated with improved neurological recovery after acute ischaemic stroke, according to a sub study of the MR CLEAN trial presented at ESC Congress today by Dr Anouchska Autar, PhD candidate at the Erasmus Medical Centre in Rotterdam, the Netherlands.1
"Acute ischaemic strokes occur when a blood clot, also called a thrombus, embolises to the brain where it restricts the flow of blood," said Dr Autar. "MR CLEAN was the first trial to show the benefit of IAT to remove blood ...
India's bread basket, the Indo-Gangetic Plains (IGP), have been classified as a "hot spot" for air pollution. A recent study from the University of Eastern highlights the current status of ozone research in the IGP region, which is agriculturally important and densely populated.
To study adverse effects of ozone, field experiments were conducted with local crop cultivars of mustard (Brassica campestris L.) and rice (Oryza sativa L.), and various growth, physiological (gas-exchange), biochemical and yield parameters were studied throughout the growing season. Ethylenediurea ...
Many volcanoes are located in densely settled areas. Every time one of these becomes active, large populations are put at risk. Hence, one of the primary goals of the current generation of volcanologists is to develop tools that can accurately predict when volcanoes will erupt. In the case of an impending eruption, these tools are of key importance to those charged with making decisions about what action to take and when. "However, the tools available for predicting eruptions are still in their infancy. We can't always successfully predict an eruption as we lack an understanding ...
Bile duct cancer is rare and is usually detected too late. Often only extensive liver surgery can help or, in rare cases, liver transplantation. But which patients will benefit from surgery and which will not, because their risk of cancer recurrence is too high? With the oncogene MACC1 as a biomarker, physicians for the first time have a tool to decide which treatment option is best for patients with Klatskin carcinoma, one type of bile duct cancer. If MACC1 expression is low, the patients have a good chance that surgery will prolong survival. By contrast, if the gene is ...
London, UK - 30 Aug 2015: Patients with atrial fibrillation who receive antithrombotic management according to ESC guidelines have better outcomes than those who do not, according to one year follow up results from the ESC's EORP-AF Pilot General Registry presented today at ESC Congress 20151 and published online in Europace. 2
"This is the first study to show better outcomes using the 2012 ESC guidelines on atrial fibrillation," said principal investigator Professor Gregory YH Lip, from the University of Birmingham, UK and Aalborg University, Denmark.3 "This is novel ...
