Using molecular genomics to understand the social behaviour of Woolly Mammoths.

The Woolly Mammoth, Mammuthus primigenius, is thought to have diverged from the earlier Steppe Mammoth Mammuthus trogontherii in northeast Asia around 700 000 years ago and by 200 000 years ago spread across Asia and into Europe and across the Bering Strait into North America. As a widespread and apparently numerous species living in the recent past they have left an extensive fossil record, primarily of isolated teeth and bones, but also including a number of mummified and frozen specimens, trapped within the Arctic permafrost. This has allowed a number of detailed anatomical and molecular studies of the Woolly Mammoth, using specimens that were excavated in the nineteenth and early twentieth centuries. Despite this wealth of data there is relatively little direct information on the behaviour of these animals available, with most of our ideas about the social structure of Mammoths based upon extrapolation from living Elephant species rather than direct evidence.

In a paper published in the journal Current Biology on 2 November 2017, Patrícia Pe cnerova of the Department of Bioinformatics and Genetics at the Swedish Museum of Natural History, and the Department of Zoology at Stockholm University, David Díez-del-Molino and Nicolas Dussex, also of the Department of Bioinformatics and Genetics at the Swedish Museum of Natural History, Tatiana Feuerborn, again of the Department of Bioinformatics and Genetics at the Swedish Museum of Natural History, amd of the Centre for GeoGenetics at the Natural History Museum of Denmark, Johanna von Seth, again of the Department of Bioinformatics and Genetics at the Swedish Museum of Natural History, and the Department of Zoology at Stockholm University, Johannes van der Plicht of the Centre for Isotope Research at Groningen University, and the Faculty of Archaeology at Leiden University, Pavel Nikolskiy of the Geological Institute of the Russian Academy of Sciences, Alexei Tikhonov of the Zoological Institute of Russian Academy of Sciences and the Institute of the Applied Ecology of the North at the North-Eastern Federal University, Sergey Vartanyan of the North-East Interdisciplinary Scientific Research Institute N.A.N.A. Shilo of the Far East Branch of the Russian Academy of Sciences, and Love Dal én, once again of the of Bioinformatics and Genetics at the Swedish Museum of Natural History, present the results of a study in which they determined the sexes of 98 Woolly Mammoth specimens from different locations in Siberia and on Wrangel Island.

 The Siegsdorfer Mammut, in the Südostbayerisches Naturkunde und Mammut-Museum, the largest complete Mammoth specimen in Europe, thought to be a male. Lou Gruber/Wikimedia Commons.

Pecnerova et al. were able to identify the sex of 95 Mammoths, of which 66 were male and 29 were female, a noteworthy and clearly significant difference. Modern Elephants, like almost all Mammals, produce male and female offspring in equal proportions, and there is no reason to suspect that Mammoths were any different in this regard, suggesting that male Mammoths were more likely to enter the fossil record than female Mammoths.

Elephants show distinct sexual dimorphism, with males significantly larger than females. As a rule of thumb, the hard tissues of larger animals are more likely to survive intact until they are buried than those of smaller animals, simply because they are harder for other animals to break down. However Pecnerova et al.do not believe that this is likely to have been a significant factor in the case of Mammoths, as all Mammoths were sufficiently large to be difficult for any other animal found in their environment to break down. Furthermore most Mammoth specimens for which data on their origins are available seem to have come from natural traps, such as sinkholes, mudflows or pools, where their remains were buried rapidly, whereas remains left on open tundra will tend to remain exposed for years or even centuries, where the action of the weather can break down even the largest bones.

Instead, Pecnerova et al. suggest that the behaviour of the Mammoths when they were alive may have played a role in how likely they were to enter the fossil record.Modern Elephants have a complex social structure, with female Elephants living in family groups with their young and each such group having a set territory which they know very well. Males leave these groups when they approach sexual maturity, and live in male groups which are much wider ranging, and less defined in structure, with the youngest males not being automatically accepted into such a group, and often having to range over very large areas before they find a male pack that will accept them - if they do so at all. The largest, sexually mature, males leave these packs, becoming intolerant of other males, particularly when they are in musth (a heightened state of sexual agitation, and range over very wide areas looking for available females.

This more adventurous lifestyle means that male Elephants, unlike females, spend much of their lives in unfamiliar territory. If the same held true for Woolly Mammoths then males of this species would have been more likely to encounter unfamiliar hazards, such as sinkholes or swamps, which females would be taught to avoid by older members of the herd if they lie within their territory. This matches closely with what is observed in the fossil record, with predominantly male specimens preserved in geographical traps, which Pecnerova et al. believe is evidence of a similar social structure in Mammoths to that in Elephants.

See also...

Follow Sciency Thoughts on Facebook.

Analysing the distribution of Pleistocene Terrestrial Vertebrate Fossils from the North Sea.

Today the UK is an island separated from the European mainland by the North Sea and English Channel, but for much of the Pleistocene the UK was attached to the rest of Europe, with large areas of land that were occupied by early Humans and other terrestrial animals. Over the past two centuries a very large number of Pleistocene Terrestrial Vertebrate Fossils have been recovered from the North Sea. Some of this has some from sites which have been the site of organised archaeological and palaeontological investigations, such as Bouldnor Cliff in the Solent (not strictly part of the North Sea), Area 240 off the north coast of Norfolk and Brown Bank and Eurogeul off the coast of the Netherlands, but the largest proportion of the material has been brought up by fishing trawlers and dredgers from areas never directly accessed by archaeologists or palaeontologists. In recent years some effort has been made to analyse North Sea material in Dutch collections in order to build up a picture of the age of the specimens, and understand the environments in which they were living.

In a paper published in the journal Antiquity on 28 June 2016, Rachel Bynoe of the Department of Archaeology at the University of Southampton, Justin Dix of the National Oceanography Centre Southampton, also at the University of Southampton, and Fraser Sturt, again of the Department of Archaeology at the University of Southampton describe the results of a study of 1120 specimens collected from the North Sea and currently in the collections of museums in the east of England.

Bynoe et al. identified three main areas targeted by large fishing fleets from the East of England in the nineteenth and twentieth centuries. The area from the Dogger Bank, northward to the Skagerrak and towards the Shetland Islands, Greenland and the Barents Sea was targeted by fleets from the ports of Grimsby and Hull, the area from Dogger Bank south to the Leman and Ower Banks was exploited by the Yarmouth Fleet and the area south of the Leman and Ower Banks, east to the Dutch coast and south to the Gabbards was utilised by the fleet from Lowestoft. In addition numerous smaller coastal fleets targeted inshore areas close to their home ports.

All locations and sites mentioned in the text, with contours showing current offshore bathymetry. Bynoe et al. (2016).

The accessible fossil record of the North Sea is known to be skewed; only the largest and most robust specimens are likely to have survived on the sea floor for thousands of years, become entangled in fishing nets then spotted by Human observers not specifically looking for fossil remains. Nevertheless even with such a bias towards large specimens some biostratigraphical and environmental reconstruction is possible; in particular considerable faunal turnover is associated with the Anglian Glaciation (roughly 478 000–424 000 years ago), when the glaciers reached as far south as London, and most specimens can be confidently described as belonging to pre- or post-Anglian Glaciation species. Likewise some species present were clearly not adapted to colder conditions (such as the Straight-tusked Elephant, Palaeoloxodon antiquus, or Narrow-nosed Rhinoceros, Stephanorhinus hemitoechus) and therefore must have lived during warm, interglacial periods.

Of the examined specimens 71% were found to have sufficient information to tie them to an approximate location. The information recorded at the time when the fossils were collected is often somewhat vague, such as 'East Coast' or 'Suffolk'; however this can be further refines, for example a specimen labelled 'Suffolk' is likely to have been collected by a fishing vessel from Lowestoft, and therefore can be assigned to the area targeted by the Lowestoft fleet. The identity of the collectors that amassed the material and donated it to the museums was also useful, for example the antiquarian John Owles is known to have collected material brought ashore by the Great Yarmouth fleet in the mid nineteenth century, so fossils collected by him and labelled 'East Coast' can be assigned to the area targeted by the Great Yarmouth fleet.

Cervus sp. skull showing Owles’s Great Yarmouth stamp. Bynoe et al. (2016).

Of the Great Yarmouth specimens 85% are considered to be post-Anglian species, with 9% pre-Anglican and 6% species present both before and after the Anglian glaciation. 68% of the post-Anglian specimens are assigned to a single species, the Woolly Mammoth, Mammuthus primigenius, with the Woolly Rhinoceros, Coelodonta antiquitatis, and the Aurochs, Bos primigenius, each making up 6% of the specimens, Reindeer, Rangifer tarandus, made up 3% of these specimens, and Walrus, Trichechus rosmarus, and Giant Deer, Megaloceros giganteus, each making up less than one percent of the specimens. The warm-climate Straight-tusked Elephant, Palaeoloxodon antiquus, was also present, albeit at a very low level.

Post-Anglian species also dominated the Lowestoft specimens, comprising 72% of the total, though here pre-Anglican specimens made up 19% of the total and species present both before and after the Anglian glaciation made up 9% of the total. Again the most abundant species in the post-Anglican set was the Woolly Mammoth, Mammuthus primigenius, though here it only made up 51% of the total, with the Aurochs, Bos primigenius, making up 9% of the specimens, and the Woolly Rhinoceros, Coelodonta antiquitatis, making up 8%.

The inshore specimens shore a more detailed picture, with the northern coast of East Anglia having an assemblage dominated by pre-Anglian specimens, with the proportion of post-Anglian specimens rising further south along the coast, with a distinct pocket of warm-climate species including Straight-tusked Elephant, Palaeoloxodon antiquus, or Narrow-nosed Rhinoceros, Stephanorhinus hemitoechus and Hippopotamus sp. found around the Tendring Peninsula, interpreted as having been deposited late in the last interglacial period; a hypothesis supported by a sediment core taken from nearby deposits that yielded an optically stimulated luminescence date of about 116 000 years ago.

(a) Changing proportions along the coastal locations; (b) changing proportions from Great Yarmouth and Lowestoft fleets, plus inset chart showing the coastal species from locations with larger sample sizes. Bynoe et al. (2016).

This data ties in well from that from the Dutch coastal sites, which are likely to overlap with the Lowestoft data, which yielded radiocarbon dates of 60 000–15 000 years ago and an environmental reconstruction that suggests the area was dominated be Mammoth Steppe; a cold grassland environment most associated with the last glaciation, appearing slightly over 100 000 years ago and disappearing about 12 000 years ago. These Dutch deposits have also produced the only known Pleistocene Human remains from the North Sea, a Neanderthal brow ridge from the Zeeland Ridges.

See also...

Evidence of cannibalism in a Neanderthal population from the Late Pleistocene of Belgium.                                                        

Mitochondrial genomes of Pleistocene Europeans provide insight into early migrations to the continent.                      Recent studies of the genomes of ancient and modern peoples have provided considerable insight into the migration of modern...

Human remains from the Middle Pleistocene of Normandy.                                                             Early and Middle Pleistocene Human remains are extremely rare in northern Europe, having to date...

Follow Sciency Thoughts on Facebook.

Understanding the demise of the last Mammoths of St Paul Island.

Mammoths, Mammuthus spp., disappeared from the mainlands of Eurasia and North America around the end of the last Pleistocene glaciation, between 14 000 and 13 200 years ago, with some populations having possibly persisted as late as 10 500 years ago. However populations of Woolly Mammoths, Mammuthus primigenius, are known to have survived on several Beringian islands long after the end of the Pleistocene, with the last populations having survived on Wrangel Island (north of Siberia) till about 4020 years ago and St. Paul Island (in the Pribilof Islands of the Bering Sea) till around 5600 years ago. The demise of the Mammoths of Wrangel Island is known to have occurred around the time the first Humans arrived on the island, suggesting strongly that they may have become extinct directly due to Human activity. However the first Humans to reach St. Paul Island thought to have arived in the late eighteenth century, long after the demise of the island's last Mammoths, suggesting that another cause must have been responsible for there demise.

In a paper published in the Proceedings of the National Academy of Sciences of the United States of America on 1 August 2016 a team of scientists led by Russell Graham of the Department of Geosciences at The Pennsylvania State University describe the results of a study into the demise of the last Mammoths of St Paul Island.

St Paul Island is thought to have been cut off from the Bering Land Bridge between 14 700 and 13 500 years ago, and shrunk rapdily in size until about 9000 years ago, then more slowly untill about 6000 years ago, when it reached approximately its current size.

The previous last recorded date for Mammoths on St Paul Island was about 6480 years ago, but such dates are not generally thought to represent the last actual date a species was present. Graham et al. carried out radiocarbon dating of collagen from 14 newly discovered Mammoth remains from the island, obtaining a latest date of 5530 years ago, ~about 950 years after the previous last date for Mammoths on St Paul Island, but still ~1500 years before the last known date for Mammoths on Wrangel Island.

Map of current continents (dark gray) and the past position of the Bering Land Bridge (light gray) with red boxes indicating Wrangel Island (Upper) and St. Paul Island (Lower). Graham et al. (2016).

Graham et al. then examined a series of sediment cores from Lake Hill, a freshwater lake near the center of the island, and the largest and deepest body of water on the island at about 1.3 m. These were then examined for four different climatic proxies across the period when the Mammoths disappeared. These were the spores of three coprophilous Fungi (species that specialize in growing on animal dung) Sporormiella, Sordaria, and Podospora and the presence and nature of sedimentary DNA. The general environement was reconstructed across this period using a variety of proxies including Cladocerans, Diatoms, pollen, plant macroremains, and stable isotopes, and dated using radiocarbon dates from the plant macroremains and tephrochronology (isotope dates from volcanic ash layers).

Mammoth DNA was present in soil samples till about 5650 years ago, while the coprophilous Fungi Sporormiella and Sordaria disappeared 5680 and 5650 years ago respectively (Podospora disappeared much earlier), supporting the idea that the last Mammoths lived on the island about five and a half milenia ago. 

This date coencides with a marked drying of the environment on the island, as indicated by the environmental proxies. Species of Cladocerans and Diatoms associated with a planktonic lifestyle in clear, deep, lake waters disappear, and are replaced by specues associated with shallow, turbid (muddy) waters. 

This timing also coencides with a period of increased climatic instability recorded in other parts of the Aluetian Islands and Alaska, which would be consistent with reduced rainfall on the island lowering the availability of fresh water. Modern Indian and African Elephants consume between 70 and 200 litres of water per day, and Mammoths are likely to have had similar requirements, suggesting that any such draught could have hit a small island population very hard. Under such circumstances the Mammoths may have been forced to crowd around a few greatly reduced water sources, which would have led to further environmental degredation, causing increased erosion around the pools and degrading the water quality.

See also...

X-ray Computed Tomography studies of two Woolly Mammoth calves from Russia.            The Woolly Mammoth, Mammuthus primigenius, is thought to have diverged from the earlier Steppe Mammoth Mammuthus trogontherii in northeast...

The Dwarf Pachyderms of Crete, Mammoths or Straight-Tusked Elephants?                  Fossil Dwarf Elephants are known from a number of small islands around the world; this is not altogether surprising, dwarfism is common in populations of animals cut of on small islands (as is giantism). Animals in such environments often need to adapt to...

What Nitrogen tells us about the diet of Mammoths.                                             Nitrogen has two stable isotopes, Nitrogen-14 (¹⁴N) and Nitrogen-15 (¹⁵N), which have different atomic weights, but identical chemical properties, and can be incorporated into identical compounds by...

Follow Sciency Thoughts on Facebook.

X-ray Computed Tomography studies of two Woolly Mammoth calves from Russia.

The Woolly Mammoth, Mammuthus primigenius, is thought to have diverged from the earlier Steppe Mammoth Mammuthus trogontherii in northeast Asia around 700 000 years ago and by 200 000 years ago spread across Asia and into Europe and across the Bering Strait into North America, where they hybridized with the Columbian Mammoth Mammuthus columbi. They are believed to have been the last surviving species of Mammoth, persisting to as late as 3700 years ago on Wrangel Island, off the northeast coast of Siberia (with some claims of even more recent specimens). As a widespread and apparently numerous species living in the recent past they have left an extensive fossil record, primarily of isolated teeth and bones, but also including a number of mummified and frozen specimens, trapped within the Arctic permafrost. These have allowed a number of detailed anatomical and molecular studies of the Woolly Mammoth, although many were excavated in the nineteenth and early twentieth centuries, and have subsequently degraded due to poor storage facilities, preventing the application of the most modern methods to these specimens.

In a paper published in the Journal of Paleontology in July 2014, a team of scientists led by Daniel Fisher of the Museum of Paleontology at the University of Michigan describe the results of a series of X-ray Computed Tomography studies of two recently discovered Woolly Mammoth calves from permafrost in the Siberian Arctic.

The first specimen, named Lyuba, was found in May 2007 by on a bank of the Yuribei River on the Yamal Peninsula, where it is believed to have been deposited by an ice-melt flood the previous spring. When found it was almost intact, having lost only its hair and nails, however it was transported to a nearby village where it was partially scavenged by domestic Dogs, losing part of the tail and right ear, before being acquired by the Shemanovskiy Museum and Exhibition Center in Salekhard in the Yamalo-Nenets Autonomous Okrug of the Russian Federation. Here the specimen was found to be partially dehydrated, having lost approximately half of its expected water content, and found to be female by examination of the urogenital tract, and subsequent DNA analysis.

Lyuba’s body was found to have been acidified, probably by colonization of the corpse by lactic acid-producing Bacteria, leading to the degradation of much of the connective tissue (collagen). The facial region was found to contain numerous masses of vivianite (hydrated iron phosphate). Examination of Lyuba’s teeth was able to find a neonatal line (produced at the time of birth) followed by 30-35 daily growth increment lines, setting her age at the time of death at 30-35 days. She appears to have been healthy and well fed at the time of her death. An isotopic analysis of the age of the body suggested an age of about 41 800 years.

Lyuba was subjected to a full CT scan, then examined endoscopically through two holes drilled in her left side. She then underwent two necropsy sessions, in which her body was thawed, partially dissected then refrozen. In the first the teeth were removed from the left side of the face, and portions of the large and small intestine were also extracted. In the second the pleural and abdominal cavities were examined. At this point it was determined by the Shemanovskiy Museum that the body would need to be treated chemically to prevent further decomposition, and allowed to dehydrate fully.

Fisher et al. were unable to access the original CT scans of Lyuba made at the Shemanovskiy Museum before chemical treatment. However they were able to take the body to the GE Healthcare Institute in Waukesha, Wisconsin, where it was possible to scan the Mammoth’s head and neck and a portion of the right forelimb and (separately) her pelvic region and left hind limb (the entire Mammoth was too large to fit into the scanning equipment at Waukesha). A complete scan of the Mammoth’s body was later made at the Nondestructive Evaluation Laboratory of the Ford Motor Company in Livonia, Michigan (as far as Fisher et al. are aware this is the first time a Mammoth has undergone a complete full-body scan in this way). Unfortunately industrial scanners like the one at Livonia are slower than medical models, and only seventeen hours were available for the scans on Lyuba, so the resolution achieved was not as high as hoped. Micro CT scans of the extracted teeth were carried out at the University of Michigan Dental School in Ann Arbor, Michigan.

Lyuba was already known to have significant sediment lodged within her trunk. Her oral cavity (mouth) was also filled with sediment, although this matched the bank sediment at the site by the Yuribei River where she was found, so it is assumed that this was emplaced during the recent transportation of the body. The second necropsy carried out on Lyuba was able to determine that her lungs had collapsed, and that larger bronchial cavities were filled with a bright blue powder identified as vivianite with some clay minerals. The CT scans revealed that Lyuba’s trachea was also filled with material which had the same density as the material in both the trunk and lungs, suggesting that all three are the same.

Fisher et al. suggest that Lyuba died after inhaling mud which blocked her trachea and the front part of the bronchial system in her lungs, preventing her from breathing and leading to suffocation; this matches the distribution of sediment seen in the trachea and lungs and the collapse of the other lung tissue (in the alternative scenario, drowning, sediment would have spread throughout the lungs, which would not have collapsed. It is impossible to assess where this happened, as the body had been transported prior to its discovery, but fine-grained vivianite is typical of lake-bottom sediments.

Aspirated sediment in the Mammoth calf Lyuba, sediment with a radiodensity in the range of bone can be traced from the pharyngeal region,through the trachea, and into the lung bronchi (from the Ford scan). Fisher et al. (2014).

The first vivianite detected on Lyuba was found on her left side, which was the side she was laying on when discovered, wher a number of circular pit where filled with bright blue material. This is interpreted to have been caused by fungal growth, which has previously been documented on a number of other specimens of similar age, including the ‘Blue Babe’ Steppe Bison mummy and the Tyrolian iceman ‘Otzi’. However vivianite was also found in nodules throughout the facial region of Lyuba, and within the diaphyses of her long bones (the growing ends of the long bones in a young mammal), where a better explanation was needed.

Fisher et al. suggest that this is connected closely to the manner of Lyuba’s death. If she did asphyxiate on lake bottom sediments, then it is likely that she was in a cold, wet environment suffering from oxygen deprivation immediately prior to death. Mammals in such circumstances have a ‘diving reflex’, whereby blood is withdrawn from the skin and extremities, but the supply increased to the face and brain, thereby keeping the animal alive as it tries to escape its predicament. Vivianite is an iron-phosphorous mineral, and needs a supply of both elements to form. In the case of the facial nodules the iron comes from blood pumped to the head as Lyuba struggled for her life, while the phosphorus comes from the dissolution of bone tissue by the action of lactic-acid forming Bacteria after her death. In the case of the long bone diaphyses the iron would have come from bone marrow, which is particularly rich in iron in these areas of bone growth.

Larger elements of Lyuba’s appendicular skeleton (without maniand pedes) extracted from the Ford scan: (1) radiodense nodules withindeveloping trabecular spaces in long bones are probably vivianite crystalsformed from bone-derived phosphate and blood- and marrow-derived iron;bones show radiodensity disparity between diaphyses and epiphyses; rightlateral aspect, hind limbs on left (right ahead of left) and forelimbs on right(right ahead of left); (2) left humerus in anterior aspect,diaphysis (green) segmented separately from epiphyseal ossifications(labeled); (3) segmented radiodense nodules show through cortical bone of diaphysis (humerus unsegmented in this image so that nodules show through);common scale for 2 and 3. Fisher et al. (2013).

Lyuba’s ribcage had been laterally compressed (squashed from the sides) after death, with the greatest amount of deformation occurring on the left side. Her backbone is intact, and appears to be in life position. Her skull is also slightly deformed and compressed, which may have been aided by partial dissolution of the bone by lactic acid.

The second Mammoth calf, Khroma, was found preserved in situ, upright in permafrost near the Khroma River in northern Yakutia in October 2008, and subsequently excavated and shipped to the Mammoth Museum at the Institute of Applied Ecology of the North at North-East Federal University in Yakutsk in the Sakha Republic. At the time of discovery it had been partially eroded from the sediment, and parts of the head trunk and shoulders scavenged by Ravens and (possibly) Arctic Foxes. Thus, while in generally good condition, the body had lost much of the trunk, the flesh from the head, the fatty tissue from the back of the neck (where a fatty hump would be expected) and the heart and lungs. DNA analysis showed Khroma to be female, which was subsequently confirmed by CT scanning of the urogenital tract. A necropsy revealed she had abundant subcutaneous fat, and undigested milk in her stomach. It was not possible to determine the age of Khroma isotopically, suggesting she died more than 45  000 years ago.

Khroma was also subjected to two rounds of CT scanning, first at the Centre Hospitalier Universitaire de Clermont-Ferrand, then at the CentreHospitalier Emile Roux in Le Puy-en-Velay, both in France. Her teeth were also extracted and micro CT scanned at the at the University of Michigan Dental School in Ann Arbor, Michigan.

Examination of Khroma’s teeth enabled the detection of a neonatal line, followed by at least 52 daily growth increment lines, although these were somewhat unclear, leading Fisher et al. to conclude that she was 52-57 days old at the time of her death.

Khroma’s age, determined from her right dP3: (1) right image shows lingual aspect of a slab cut from the right dP3, anterior to the left; (2) enlargedview of the anterior root in 1; the dark line running vertically, parallel to the pulp cavity surface, is the neonatal line (NnL); (3) photomicrograph of a thin sectionof the anterior root, with pulp cavity (pc) surface at right, neonatal line (NnL) at left, and 52 or more daily dentin increments (small white dots) between them; (4) enlargement of area designated in (3), showing increments for last 18 days of life. Fisher et al.estimate Khroma’s age at death as 52–57 days. Fisher et al. (2013).

Elephants walk on a thick pad of fat with a thick layer of skin over it. The distal phalanges (bones at the tips of the toes) are believed to help distribute weight evenly within this structure, though exactly how this works is unclear. In African Elephants only the third and fourth toes have ossified (bone) distal phalanges, with these elements in the other toes being cartilage, while in Asian Elephants the distal phalanges of toes two, three and four are ossified. Attempts to resolve the number of ossified distal phalanges in Mammoths have been, to date, unsuccessful, largely as the limb tips are seldom preserved intact.

Khroma was preserved with her feet undamaged, making analysis of the ossification state in the distal phalanges a possibility. Unfortunately no ossified distal phalanges could be detected, nor was it possible to detect ossification in the metatarsal-phalangeal sesamoid (known to ossify in Woolly Mammoths), suggesting that Khroma was too young at the time of death for complete ossification of all the bones in the foot to have occurred. However it was possible to detect the synovial capsules in the foot (fluid filled capsules that form between bone-bone joints in Mammals, but not bone-cartilage joints), as these had lost their fluid but filled with (distinctly less dense) air. This suggests that the second, third, fourth and fifth distal phalanges may have ossified.

Khroma’s left hind foot: (1) lateral aspect, anterior to left,showing nucleation sites and epiphyseal ossification center on calcaneumtuber at right; (2) anterior aspect; (3) anterior aspect, synovial joint capsules ondigits, light blue; (4) anterior aspect, non-terminal joint capsules light blue andterminal joint capsules purple. Abbreviations: Ast., astragalus; Cal., calcaneum; Cub., cuboid; Ect., ectocuneiform; Ent., entocuneiform; IP, intermediate phalanx; Mes., mesocuneiform; MT, metatarsal; MT I, metatarsal I (red); MT V, metatarsal V (blue diaphysis); PP, proximalphalanx. Separate scales for 1 and 2; common scale for 3 and 4. Fisher et al. (2013).

Khroma’s skeleton was more damaged than Lyuba’s, with some of the ribs broken by recent scavenging, and a break between the seventh and eighth thoracic vertebrae, which occurred at about the time of death. Khroma is thought to have died of sediment inhalation in a similar way to Lyuba, but this break suggests a much more violent setting (the backbones of even very small Elephants are quite robust). Fisher et al. suggest that she may have been caught in a mud flow or bank collapse, which caused a significant lateral impact as well as burying her and preventing breathing.

 Khroma’s ribcage in right lateral aspect (interruption of rib sequence caused by break in vertebral column). Fisher et al. (2013).

See also…

The Dwarf Pachyderms of Crete, Mammoths or Straight-Tusked Elephants?

Fossil Dwarf Elephants are known from a number of small islands around the world; this is not altogether surprising, dwarfism is common in populations of animals cut of on small islands (as is giantism). Animals in such environments often need to adapt to different niches to those they inhabit on larger land-masses, but are able to do so due to lack of competition, since there...

What Nitrogen tells us about the diet of Mammoths.

Nitrogen has two stable isotopes, Nitrogen-14 (¹⁴N) and Nitrogen-15 (¹⁵N), which have different atomic weights, but identical chemical properties, and can be incorporated into identical compounds by organisms. Nitrogen fixing organisms (diazotrophs) tend to fix Nitrogen isotopes in the ratio found in the atmosphere, but each time the Nitrogen is passed from one...

Elephant trackways from the United Arab Emirates.

Elephants have a long and well understood fossil record, but this can usually only tell us about the physical attributes of Elephants, i.e. their...

Follow Scieny Thoughts on Facebook.

What Nitrogen tells us about the diet of Mammoths.

Nitrogen has two stable isotopes, Nitrogen-14 (¹⁴N) and Nitrogen-15 (¹⁵N), which have different atomic weights, but identical chemical properties, and can be incorporated into identical compounds by organisms. Nitrogen fixing organisms (diazotrophs) tend to fix Nitrogen isotopes in the ratio found in the atmosphere, but each time the Nitrogen is passed from one organism to another, some of it is lost, with the lighter ¹⁴N being lost more rapidly than the heavier ¹⁵N. This makes it possible for scientists to estimate where an animal sits in the food chain from the proportion of ¹⁵N (δ¹⁵N) in compounds it produces; for example herbivores have a high δ¹⁵N compared to plants, and carnivores have a higher δ¹⁵N than herbivores.

Collagen from the bones of Woolly Mammoths (Mammuthus primigenius) typically has δ¹⁵N values about 3‰ higher than similar collagen from other herbivores from the same environment (tundra grasslands) such as Rhinoceroses (Coelodonta antiquus) and Horses (Equus sp.). Such a high comparative proportion of ¹⁵N would usually be taken as an indication of being a stage higher on the food chain, but Mammoths were clearly not well adapted to predating either Horses or Rhinoceroses, and even if this was not immediately obvious, there have been numerous studies of the stomach contents of frozen Mammoths, none of which have suggested that they were carnivorous.

A Woolly Mammoth, not likely to have been a predatory animal. Laurie Caple.

In a paper published in the journal Archaeological and Anthropological Sciences on 14 April 2012, Margot Kuitems, Thijs van Kolfschoten and Johannes van der Plicht of the Faculty of Archaeology at Leiden University present the results of an investigation into the δ¹⁵N values of keratin in the nails and hooves of Elephants, Rhinoceroses and Horses in a number of Dutch zoos and riding schools, and discuss the conclusions drawn from these results.

In 1986 Stanley Ambrose and Michael DeNiro of the Department of Earth and Space Sciences at the University of California, Los Angeles published a paper in the journal Oecologia, detailing the results of a study into the Carbon and Nitrogen isotope ratios in collagen from the bones of large mammals from the grasslands of Kenya and Tanzania. This revealed that like Pleistocene Mammoths, East African Elephants had raised δ¹⁵N compared to other large herbivores in the same environment. This led Kuitems et al. to conclude that modern Elephants could serve as a substitute for Wooly Mammoths in an investigation into Nitrogen isotope ratios in proteins.

Elephants in the Mwaluganje Elephant Sanctuary in Kenya. Although African Elephants are not closely related to Woolly Mammoths they also show raised δ¹⁵N compared to other large herbivores in the same environment, making them a good experimental model. Lonely Planet.

Keratin from nails is not an exact analogue for collagen from bones, but was more readily available; Kuitems et al. found that bones of deceased animals from Dutch zoos were collected by the Faculty of Veterinary Science of the University of Utrecht, but than they were cleaned with aggressive cleaning agents that rendered them useless for the purpose of this study.

In the event the study found no appreciable differences between the δ¹⁵N values in keratin from the three groups of animals yielded no appreciable variation, but this in itself was not a total disaster. Elephants (and other animals) in Dutch zoos are well fed the year round; they are not subject to the periodic environmental stresses that animals living in the wild have to endure. This suggests that the Nitrogen isotope imbalance seen in the bones of Mammoths and African Elephants is the result of environmental stress, rather than something that stems automatically from Elephant metabolism or behavior.

Kuitems et al. observed that Elephants have quite short guts for their size compared to Horses or Rhinoceroses, making them less efficient at food processing. This would mean that in times of short food supply they would be more reliant on recycling Nitrogen internally, which would tend to raise their δ¹⁵N value. This would be further increased if the Elephants were to engage in coprophagy, eating their own dung, a good strategy for a herbivore with a short digestive tract. This was not observed in the (well fed) Dutch zoo Elephants, but could still be a possibility in wild East African Elephants and Pleistocene Mammoths.

See also Did Spotted Hyenas colonize Britain once or twice? What killed the Australian Thylacine, What a 4.6 million-year-old Three Toed Horse can tell us about the climate of Mid Pliocene Tibet, Elephant trackways from the United Arab Emirates and Mammals on Sciency Thoughts YouTube.

Follow Sciency Thoughts on Facebook.