Haramiyida
Encyclopedia
Haramiyidans seem to be the earliest known herbivore
s amongst basal mammal
s, assuming they are mammals. Their teeth, which are by far the most common remains, resemble those of the multituberculates. The jaw however, based on Haramiyavia, is less derived; "at the level of evolution of Morganucodon and Kuehneotherium, with a groove for ear ossicles
on the dentary".
“Jenkins’ group identified haramiyid jaws with the teeth in place, as well as additional parts of the skeleton. Among other revelations from the fossils, the teeth in the upper jaw do not fit the classic multituberculate arrangement, with the second molar offset towards the centre of the mouth.
“That shows rather well that haramiyids are not closely related to multituberculates,” says William A. Clemens of the University of California, Berkeley
, one of the leaders of the multituberculate symposium. This taxon is in some disgrace for being paraphyletic; i.e. it doesn’t consist of one ancestor species and its descendants. Kemp provides a concise overview of the post-canine
s. Harami Molars
are larger than many of their equivalents from contemporary mammals, but not by much. These have many of cusps
and are generally double-rooted
. The crowns
are wide and have a line of three large cusps on one edge, with five smaller ones on the opposing side.
Originally, it was thought that upper and lower molars were pretty much mirror images of each other, and minor details lead to the establishment of two genera: Thomasia
and Haramiya. The suggestion was subsequently made that these could also represent lowers and uppers of only one genus, and the discovery of Haramiyavia provided confirmation for that. The teeth of Theroteinida and Eleutherodontida, (nothing more is yet known), are perhaps more accurately described as 'haramiyidan'-like. "But haramiyids are known from beds as old as Norian: hence, if they are related to multituberculates, an astonishingly early divergence of crown mammals (not to mention a series of putative sister taxa to crown mammals) is implied,".
More precise affinities will probably remain unclear until better evidence is forthcoming. Butler & Hooker, (2005) maintain that 'haramiyids' are still stronger candidates for having given rise to the multituberculates than morganucodon
tids are: "As long as we only have teeth to of the critical taxa, we feel it necessary to adopt the Allotheria
concept as a working hypothesis; no doubt the discovery of mammalian skeletal material in the Jurassic
will throw new light on the problem", (p. 206). The concept of Allotheria unites haramis and multituberculates as the sister line of other mammals.
Most fossils have been reported from Europe, but some are known from Africa and Greenland. A description in January 2005 extended the published range to the Junggar Basin
of Inner Mongolia
. It may be safer to refer to this group as haramyioidens rather than 'haramiyidans'. 'Haramiyan' fossils first appear in the Upper Triassic
. Until 1999, the last traces were Middle Jurassic
. However, Allostaffia then turned up in the Upper Jurassic
of Tanzania
.
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s amongst basal mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, assuming they are mammals. Their teeth, which are by far the most common remains, resemble those of the multituberculates. The jaw however, based on Haramiyavia, is less derived; "at the level of evolution of Morganucodon and Kuehneotherium, with a groove for ear ossicles
Ossicles
The ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth . The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss...
on the dentary".
Ancestry
It is tempting to infer that this order represents the ancestors of the multituberculates, a group which appears to have survived until about 40 million years ago. While this is not impossible, the evidence available is insufficient to be conclusive. As an illustration and with reference to material from Greenland:“Jenkins’ group identified haramiyid jaws with the teeth in place, as well as additional parts of the skeleton. Among other revelations from the fossils, the teeth in the upper jaw do not fit the classic multituberculate arrangement, with the second molar offset towards the centre of the mouth.
“That shows rather well that haramiyids are not closely related to multituberculates,” says William A. Clemens of the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, one of the leaders of the multituberculate symposium. This taxon is in some disgrace for being paraphyletic; i.e. it doesn’t consist of one ancestor species and its descendants. Kemp provides a concise overview of the post-canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
s. Harami Molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
are larger than many of their equivalents from contemporary mammals, but not by much. These have many of cusps
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
and are generally double-rooted
Root canal
A root canal is the space within the root of a tooth. It is part of a naturally occurring space within a tooth that consists of the pulp chamber , the main canal, and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root.-Root canal anatomy:...
. The crowns
Crown (tooth)
In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. The crown is usually visible in the mouth after developing below the gingiva and then erupting into place.-References:...
are wide and have a line of three large cusps on one edge, with five smaller ones on the opposing side.
Originally, it was thought that upper and lower molars were pretty much mirror images of each other, and minor details lead to the establishment of two genera: Thomasia
Thomasia
Thomasia is a genus of plants which are native to southern Australia. All but one species is restricted to the Southwest Botanical Province of Western Australia; the other occurs in South Australia and Victoria.Species include:...
and Haramiya. The suggestion was subsequently made that these could also represent lowers and uppers of only one genus, and the discovery of Haramiyavia provided confirmation for that. The teeth of Theroteinida and Eleutherodontida, (nothing more is yet known), are perhaps more accurately described as 'haramiyidan'-like. "But haramiyids are known from beds as old as Norian: hence, if they are related to multituberculates, an astonishingly early divergence of crown mammals (not to mention a series of putative sister taxa to crown mammals) is implied,".
More precise affinities will probably remain unclear until better evidence is forthcoming. Butler & Hooker, (2005) maintain that 'haramiyids' are still stronger candidates for having given rise to the multituberculates than morganucodon
Morganucodon
Morganucodon is an early mammalian genus which lived during the Late Triassic. It first appeared about 205 million years ago. This has also been identified with Eozostrodon. Unlike many other early mammals, Morganucodon is well represented by abundant and well preserved, though in the vast...
tids are: "As long as we only have teeth to of the critical taxa, we feel it necessary to adopt the Allotheria
Allotheria
Allotheria was a branch of successful Mesozoic mammals. The most important characteristic was the presence of lower molariform teeth equipped with two longitudinal rows of cusps...
concept as a working hypothesis; no doubt the discovery of mammalian skeletal material in the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
will throw new light on the problem", (p. 206). The concept of Allotheria unites haramis and multituberculates as the sister line of other mammals.
Most fossils have been reported from Europe, but some are known from Africa and Greenland. A description in January 2005 extended the published range to the Junggar Basin
Dzungaria
Dzungaria, also called Zungaria, is a geographical region in northwest China corresponding to the northern half of Xinjiang. It covers approximately , lying mostly within Xinjiang, and extending into western Mongolia and eastern Kazakhstan...
of Inner Mongolia
Inner Mongolia
Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...
. It may be safer to refer to this group as haramyioidens rather than 'haramiyidans'. 'Haramiyan' fossils first appear in the Upper Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
. Until 1999, the last traces were Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
. However, Allostaffia then turned up in the Upper Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
.
External links
- Palaeos, Mammaliaformes: Allotheria
- http://cougarhillweb.org/mammals.pdfJohn H Burkitt, Mammals, A World Listing of Living and Extinct SpeciesExtinct speciesThis page features extinct species, organisms that have become extinct.* List of extinct animals* List of extinct plants...
] - T Mike Keesey, The Dinosauricon, Ages of the Mesozoic
- Mikko K Haaramo, Haramiyida