Mesembriornis
Encyclopedia
Mesembriornis is a genus
of intermediate-sized phorusrhacids (better known as "terror bird") that grew up to 1.5 meters in height. They represent a well-distinct lineage of terror birds, differing from the massive large groups and the smaller Psilopterinae. In general proportions, they most resembled the Patagornithinae which flourished somewhat earlier, mainly to the south of the range of Mesembriornis.
Two species
are nowadays accepted, Mesembriornis incertus and Mesembriornis milneedwardsi. Mesembriornis lived on the pampa
of E and NW Argentina
from the Late Miocene
to the Late Pliocene
, roughly 10–2 million years ago. Together with the North America
n giant Titanis walleri, it was among the last terror birds alive.
"Crushing Kicks"
A group of scientists have suggested that terror birds had bone-shattering kicks. They may have used this kick to take down prey or defend kills. If it also attained the speed first thought as well as this kick, it could not have been forced off kills as easily as cheetahs in Africa.
"Cheetah of the Tertiary"
This school of thought suggests Mesmbriornis may have lived akin to a modern day cheetah
, eating the smaller notoungulate mammals of the time (Miocene) using its speed to outrun the beasts. Its top speed is a matter of debate, but estimates go up to 90 kilometers per hour. Some other scientists like to scale down the predators speed to 85, 80, 75 or even the average phorusrhacid speed of 70 km/h.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of intermediate-sized phorusrhacids (better known as "terror bird") that grew up to 1.5 meters in height. They represent a well-distinct lineage of terror birds, differing from the massive large groups and the smaller Psilopterinae. In general proportions, they most resembled the Patagornithinae which flourished somewhat earlier, mainly to the south of the range of Mesembriornis.
Two species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are nowadays accepted, Mesembriornis incertus and Mesembriornis milneedwardsi. Mesembriornis lived on the pampa
Pampa
The Pampas are the fertile South American lowlands, covering more than , that include the Argentine provinces of Buenos Aires, La Pampa, Santa Fe, Entre Ríos and Córdoba, most of Uruguay, and the southernmost Brazilian State, Rio Grande do Sul...
of E and NW Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
from the Late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
to the Late Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
, roughly 10–2 million years ago. Together with the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n giant Titanis walleri, it was among the last terror birds alive.
Debate on Mesembriornis habits
A study called "Terror Birds on the Run" measured how fast ancient terror birds could run. It was found that a terror bird's average top speed was 70 km/h (45 mph), and this is not heavily disputed. However the speed of Mesembriornis is now heavily debated. This is probably because the method of calculation was not as accurate as other mathematical methods. These methods are impossible because, like other terror birds, this beast's bones are fragmentary. There are two main theories about how Mesembriornis hunted:"Crushing Kicks"
A group of scientists have suggested that terror birds had bone-shattering kicks. They may have used this kick to take down prey or defend kills. If it also attained the speed first thought as well as this kick, it could not have been forced off kills as easily as cheetahs in Africa.
"Cheetah of the Tertiary"
This school of thought suggests Mesmbriornis may have lived akin to a modern day cheetah
Cheetah
The cheetah is a large-sized feline inhabiting most of Africa and parts of the Middle East. The cheetah is the only extant member of the genus Acinonyx, most notable for modifications in the species' paws...
, eating the smaller notoungulate mammals of the time (Miocene) using its speed to outrun the beasts. Its top speed is a matter of debate, but estimates go up to 90 kilometers per hour. Some other scientists like to scale down the predators speed to 85, 80, 75 or even the average phorusrhacid speed of 70 km/h.
External links
- http://news.nationalgeographic.com/news/2005/08/0801_050801_terrorbirds_2.html
- http://darrennaish.blogspot.com/2006/11/more-on-phorusrhacids-biggest-fastest.html
- http://www.journals.royalsoc.ac.uk/content/a9req1kl5wfc1kl4/
- http://dubitable.com/?q=aggregator&page=15&from=100