Post by Infinity Blade on Mar 30, 2015 4:55:06 GMT 5
Irish Elk-Megaloceros giganteus
Life restoration of two male M. giganteus fighting. Coloration may not be completely accurate in this illustration (see below). © @ Flavia Strani->
Temporal range: Quaternary; ~450,000[1]-7,700[2][3] years ago (Middle Pleistocene to early Holocene; Chibanian to Northgrippian)
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Suborder: Cynodontia
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
Clade: Ungulata
(unranked): Cetartiodactyla
Clade: Artiofabula
Clade: Cetruminantia
Clade: Ruminantiamorpha
Suborder: Rumintantia
Infraorder: Pecora
Family: Cervidae
Subfamily: Cervinae
Genus: †Megaloceros
Species: †M. giganteus
The Irish elk (Megaloceros giganteus) is a species of large cervid that lived in Eurasia from the Pleistocene to Holocene epochs ~450,000 (or 400,000-300,000)[1] to ~7,700[2][3] years ago. Its remains are most well known from its fossil occurrences in Irish peat bogs dating to around 11,000 years ago.[1]
Description and paleobiology:
The Irish elk is most well known for the massive set of antlers present in males. These antlers could weigh 40 kg[4] and span from 10-12 feet in large stags.[5] Andrew Kitchener proposed that the Irish elk could, in fact, use these antlers for agnostic behavior[6], notwithstanding Stephen Jay Gould's notion that they were poorly adapted for such behavior within males from a morphological standpoint, but perfect for intimidation and sexual display.[5] A 2019 study performed a finite element analysis on the antlers of M. giganteus, and compared them with the antlers of three extant deer species: red deer (Cervus elaphus), fallow deer (Dama dama), and moose (Alces alces). This analysis found that, while the Irish elk’s antlers could withstand some fighting loads, they needed to be interlocked proximally, and they were best at withstanding twisting as opposed to pushing loads, like other palmate antlers. Overall, intraspecific fighting in M. giganteus would probably have been more constrained and predictable than in extant deer.[7] Although the Irish elk possessed immense antlers, relative to body mass they were no larger than those of some extant cervids. A very big stag weighing 650 kg with antlers weighing 45 kg would only have a relative antler mass of 7.1 g/wtkg. Large fallow deer bucks and even some exceptional red deer stags match this, while caribou bulls far exceed this. Even so, M. giganteus carried the absolutely and relatively largest antlers amongst Old World deer.[8]
Total body mass would have been anywhere from ~540-700 kg.[4][9] This is in approximate agreement with Valerius Geist’s estimated range for stags, 450-700 kg, with an average of 575 kg. Does would probably have been ~80% male size, or 460 kg on average.[8]
Body structure is said to resemble that of caribou, except that the small hooves suggest M. giganteus preferred running on hard ground. It resembled addax, oryx, or saiga antelope, which are short-legged cursors that run on flat, unobstructed ground and run with the head low.[8]
Upper Paleolithic cave paintings provide insight into the color markings of the Irish elk. It seems to have been lightly colored, but with a dark dorsal stripe, dark lateral lines running from shoulder to haunch, a light throat patch in between dark stripes, and a dark hump. This coloration seems to have been an adaptation to minimize solar heat gain. Both sexes also possessed a short, steep hump over the shoulders. This may either be an adaptation to running (by increasing stride length) or for fat storage.[8]
Mounted skeleton of a male M. giganteus. Image source->
Mounted skeleton of a female M. giganteus at the Natural History Museum in London, England. Image source->
Behavior/Behavioral inferences:
Fossils from bogs suggest that males and females were segregated from each other during winters. This segregation implies the presence of seasonal rutting (using the antlers for relatively constrained, predictable combat as mentioned before) and polygynous mating. Male deaths were mostly a result of winterkill (read: malnutrition during winter) and mortality was highest amongst juveniles and small adults with small antlers.[10]
Evidence suggests that Irish elk stags were attracted to lakes, both in the winter and summer. In winter, the snow-covered ice served as terrain to flee across from predators. In summer, willows on alluvial flats and and shores had sufficient nutrients necessary for antler growth. It is noted that even at the peak of the species’ success, stags were barely meeting their mineral requirements. During the last years of their existence, nutritional deficits became more noticeable in their bones.[8]
As a large cervid, M. giganteus would have had a long gestation period and early rut. And as a cold-climate deer, gestation period would probably have been approximated by y=156 (wtkg), like in modern cold-climate cervids (e.g. fallow deer, sikas, etc.). As a result, an adult doe weighing 460 kg would have had a gestation period of ~274 days; if this is true, then the height of rut would have been in the second week of August. Old antlers would be shed early in March, the rate of antler growth would peak in early June, new antler growth would be complete in mid-July, and velvet would be shed in late July. If rutting season fell in summer, stags would have had the option to fatten up on nutritious early fall plant matter. A sufficient supply of fat would then allow them to select for protein rather than energy from their food in the winter. Stags would be free to acquire nutrients for new antler growth before shedding their current antlers in March.[8]
Diet:
Stable isotope analysis of M. giganteus teeth suggests that the diet of the Irish elk was based around grasses and forbs, supplemented in browse in a water stressed environment.[11] Pollen from Artemisia and other Asteraceae were also found compacted in the molars of a M. giganteus specimen.[12]
Extinction:
Reduced forage density during the Younger Dryas may have led to conflicts between sexual selection for greater body and antler size, and nutritional needs. This may have reduced the population of M. giganteus during the end of the Pleistocene, but because the species survived for a few thousand years after its end, this by itself could not have caused its extinction.[13]
The extinction of M. giganteus in western Europe is strongly linked to continued deterioration of climate and habitat productivity during the Younger Dryas, while it seems to have gone extinct in more eastern areas due to the spread of closed forest (this creature needed a mixed, partially open habitat with both graze and browse). However, extinction also seems to be correlated with the arrival of humans in the Irish elk’s habitat in Ireland and across Russia. Therefore, the extinction of the giant deer is still strongly linked to environmental factors, but a role for human hunting in its demise cannot be ruled out.[3]
References:
[1] Lister, A. M. (1994). The evolution of the giant deer, Megaloceros giganteus (Blumenbach). Zoological Journal of the Linnean Society, 112(1-2), 65-100.
[2] Stuart, A. J., Kosintsev, P. A., Higham, T. F. G., & Lister, A. M. (2004). Pleistocene to Holocene extinction dynamics in giant deer and woolly mammoth. Nature, 431(7009), 684-689.
[3] Lister, A. M., & Stuart, A. J. (2019). The extinction of the giant deer Megaloceros giganteus (Blumenbach): New radiocarbon evidence. Quaternary International, 500, 185-203.
[4] Moen, R. A., Pastor, J., & Cohen, Y. (1999). Antler growth and extinction of Irish elk. Evolutionary Ecology Research, 1(2), 235-249.
[5] Gould, S. J. (1974). The origin and function of ‘bizarre' structures: antler size and skull size in the 'Irish Elk,’ Megaloceros giganteus. Evolution, 191-220.
[6] Kitchener, A. (1987). Fighting behaviour of the extinct Irish elk. Modern Geology, 11(1.28), 1875.
[7] Klinkhamer, A. J., Woodley, N., Neenan, J. M., Parr, W. C., Clausen, P., Sánchez-Villagra, M. R., ... & Wroe, S. (2019). Head to head: the case for fighting behaviour in Megaloceros giganteus using finite-element analysis. Proceedings of the Royal Society B, 286(1912), 20191873.
[8] Geist, V. (1998). Deer of the world: their evolution, behaviour, and ecology. Stackpole books.
[9] MacPhee, R. D., & Sues, H. D. (Eds.). (1999). Extinctions in near time (Vol. 2). Springer Science & Business Media. p. 262.
[10] Anthony, D. В. Taphonomy and Herd Structure of the Extinct Irish Elk, Megaloceros giganteus.
[11] Chritz, K. L., Dyke, G. J., Zazzo, A., Lister, A. M., Monaghan, N. T., & Sigwart, J. D. (2009). Palaeobiology of an extinct Ice Age mammal: stable isotope and cementum analysis of giant deer teeth. Palaeogeography, Palaeoclimatology, Palaeoecology, 282(1-4), 133-144.
[12] Van Geel, B., Sevink, J., Mol, D., Langeveld, B. W., Van Der Ham, R. W. J. M., Van Der Kraan, C. J. M., ... & Lorenzen, E. D. (2018). Giant deer (Megaloceros giganteus) diet from Mid‐Weichselian deposits under the present North Sea inferred from molar‐embedded botanical remains. Journal of Quaternary Science, 33(8), 924-933.
[13] Gonzalez, S., Kitchener, A. C., & Lister, A. M. (2000). Survival of the Irish elk into the Holocene. Nature, 405(6788), 753-754.
Life restoration of two male M. giganteus fighting. Coloration may not be completely accurate in this illustration (see below). © @ Flavia Strani->
Temporal range: Quaternary; ~450,000[1]-7,700[2][3] years ago (Middle Pleistocene to early Holocene; Chibanian to Northgrippian)
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Suborder: Cynodontia
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
Clade: Ungulata
(unranked): Cetartiodactyla
Clade: Artiofabula
Clade: Cetruminantia
Clade: Ruminantiamorpha
Suborder: Rumintantia
Infraorder: Pecora
Family: Cervidae
Subfamily: Cervinae
Genus: †Megaloceros
Species: †M. giganteus
The Irish elk (Megaloceros giganteus) is a species of large cervid that lived in Eurasia from the Pleistocene to Holocene epochs ~450,000 (or 400,000-300,000)[1] to ~7,700[2][3] years ago. Its remains are most well known from its fossil occurrences in Irish peat bogs dating to around 11,000 years ago.[1]
Description and paleobiology:
The Irish elk is most well known for the massive set of antlers present in males. These antlers could weigh 40 kg[4] and span from 10-12 feet in large stags.[5] Andrew Kitchener proposed that the Irish elk could, in fact, use these antlers for agnostic behavior[6], notwithstanding Stephen Jay Gould's notion that they were poorly adapted for such behavior within males from a morphological standpoint, but perfect for intimidation and sexual display.[5] A 2019 study performed a finite element analysis on the antlers of M. giganteus, and compared them with the antlers of three extant deer species: red deer (Cervus elaphus), fallow deer (Dama dama), and moose (Alces alces). This analysis found that, while the Irish elk’s antlers could withstand some fighting loads, they needed to be interlocked proximally, and they were best at withstanding twisting as opposed to pushing loads, like other palmate antlers. Overall, intraspecific fighting in M. giganteus would probably have been more constrained and predictable than in extant deer.[7] Although the Irish elk possessed immense antlers, relative to body mass they were no larger than those of some extant cervids. A very big stag weighing 650 kg with antlers weighing 45 kg would only have a relative antler mass of 7.1 g/wtkg. Large fallow deer bucks and even some exceptional red deer stags match this, while caribou bulls far exceed this. Even so, M. giganteus carried the absolutely and relatively largest antlers amongst Old World deer.[8]
Total body mass would have been anywhere from ~540-700 kg.[4][9] This is in approximate agreement with Valerius Geist’s estimated range for stags, 450-700 kg, with an average of 575 kg. Does would probably have been ~80% male size, or 460 kg on average.[8]
Body structure is said to resemble that of caribou, except that the small hooves suggest M. giganteus preferred running on hard ground. It resembled addax, oryx, or saiga antelope, which are short-legged cursors that run on flat, unobstructed ground and run with the head low.[8]
Upper Paleolithic cave paintings provide insight into the color markings of the Irish elk. It seems to have been lightly colored, but with a dark dorsal stripe, dark lateral lines running from shoulder to haunch, a light throat patch in between dark stripes, and a dark hump. This coloration seems to have been an adaptation to minimize solar heat gain. Both sexes also possessed a short, steep hump over the shoulders. This may either be an adaptation to running (by increasing stride length) or for fat storage.[8]
Mounted skeleton of a male M. giganteus. Image source->
Mounted skeleton of a female M. giganteus at the Natural History Museum in London, England. Image source->
Behavior/Behavioral inferences:
Fossils from bogs suggest that males and females were segregated from each other during winters. This segregation implies the presence of seasonal rutting (using the antlers for relatively constrained, predictable combat as mentioned before) and polygynous mating. Male deaths were mostly a result of winterkill (read: malnutrition during winter) and mortality was highest amongst juveniles and small adults with small antlers.[10]
Evidence suggests that Irish elk stags were attracted to lakes, both in the winter and summer. In winter, the snow-covered ice served as terrain to flee across from predators. In summer, willows on alluvial flats and and shores had sufficient nutrients necessary for antler growth. It is noted that even at the peak of the species’ success, stags were barely meeting their mineral requirements. During the last years of their existence, nutritional deficits became more noticeable in their bones.[8]
As a large cervid, M. giganteus would have had a long gestation period and early rut. And as a cold-climate deer, gestation period would probably have been approximated by y=156 (wtkg), like in modern cold-climate cervids (e.g. fallow deer, sikas, etc.). As a result, an adult doe weighing 460 kg would have had a gestation period of ~274 days; if this is true, then the height of rut would have been in the second week of August. Old antlers would be shed early in March, the rate of antler growth would peak in early June, new antler growth would be complete in mid-July, and velvet would be shed in late July. If rutting season fell in summer, stags would have had the option to fatten up on nutritious early fall plant matter. A sufficient supply of fat would then allow them to select for protein rather than energy from their food in the winter. Stags would be free to acquire nutrients for new antler growth before shedding their current antlers in March.[8]
Diet:
Stable isotope analysis of M. giganteus teeth suggests that the diet of the Irish elk was based around grasses and forbs, supplemented in browse in a water stressed environment.[11] Pollen from Artemisia and other Asteraceae were also found compacted in the molars of a M. giganteus specimen.[12]
Extinction:
Reduced forage density during the Younger Dryas may have led to conflicts between sexual selection for greater body and antler size, and nutritional needs. This may have reduced the population of M. giganteus during the end of the Pleistocene, but because the species survived for a few thousand years after its end, this by itself could not have caused its extinction.[13]
The extinction of M. giganteus in western Europe is strongly linked to continued deterioration of climate and habitat productivity during the Younger Dryas, while it seems to have gone extinct in more eastern areas due to the spread of closed forest (this creature needed a mixed, partially open habitat with both graze and browse). However, extinction also seems to be correlated with the arrival of humans in the Irish elk’s habitat in Ireland and across Russia. Therefore, the extinction of the giant deer is still strongly linked to environmental factors, but a role for human hunting in its demise cannot be ruled out.[3]
References:
[1] Lister, A. M. (1994). The evolution of the giant deer, Megaloceros giganteus (Blumenbach). Zoological Journal of the Linnean Society, 112(1-2), 65-100.
[2] Stuart, A. J., Kosintsev, P. A., Higham, T. F. G., & Lister, A. M. (2004). Pleistocene to Holocene extinction dynamics in giant deer and woolly mammoth. Nature, 431(7009), 684-689.
[3] Lister, A. M., & Stuart, A. J. (2019). The extinction of the giant deer Megaloceros giganteus (Blumenbach): New radiocarbon evidence. Quaternary International, 500, 185-203.
[4] Moen, R. A., Pastor, J., & Cohen, Y. (1999). Antler growth and extinction of Irish elk. Evolutionary Ecology Research, 1(2), 235-249.
[5] Gould, S. J. (1974). The origin and function of ‘bizarre' structures: antler size and skull size in the 'Irish Elk,’ Megaloceros giganteus. Evolution, 191-220.
[6] Kitchener, A. (1987). Fighting behaviour of the extinct Irish elk. Modern Geology, 11(1.28), 1875.
[7] Klinkhamer, A. J., Woodley, N., Neenan, J. M., Parr, W. C., Clausen, P., Sánchez-Villagra, M. R., ... & Wroe, S. (2019). Head to head: the case for fighting behaviour in Megaloceros giganteus using finite-element analysis. Proceedings of the Royal Society B, 286(1912), 20191873.
[8] Geist, V. (1998). Deer of the world: their evolution, behaviour, and ecology. Stackpole books.
[9] MacPhee, R. D., & Sues, H. D. (Eds.). (1999). Extinctions in near time (Vol. 2). Springer Science & Business Media. p. 262.
[10] Anthony, D. В. Taphonomy and Herd Structure of the Extinct Irish Elk, Megaloceros giganteus.
[11] Chritz, K. L., Dyke, G. J., Zazzo, A., Lister, A. M., Monaghan, N. T., & Sigwart, J. D. (2009). Palaeobiology of an extinct Ice Age mammal: stable isotope and cementum analysis of giant deer teeth. Palaeogeography, Palaeoclimatology, Palaeoecology, 282(1-4), 133-144.
[12] Van Geel, B., Sevink, J., Mol, D., Langeveld, B. W., Van Der Ham, R. W. J. M., Van Der Kraan, C. J. M., ... & Lorenzen, E. D. (2018). Giant deer (Megaloceros giganteus) diet from Mid‐Weichselian deposits under the present North Sea inferred from molar‐embedded botanical remains. Journal of Quaternary Science, 33(8), 924-933.
[13] Gonzalez, S., Kitchener, A. C., & Lister, A. M. (2000). Survival of the Irish elk into the Holocene. Nature, 405(6788), 753-754.
