The Woolly Mammoth was one of the most iconic prehistoric mammals, roaming the icy tundras of Europe, Asia, and North America during the Pleistocene epoch. This magnificent creature was well-adapted to cold environments with its long, thick fur, massive curved tusks, and specialized physiological features.

Recent studies of mammoth DNA have revealed fascinating details about their genetic makeup. Researchers have sequenced nearly complete genomes from several specimens, showing that woolly mammoths had genetic adaptations for cold tolerance, including genes related to fat metabolism, hair growth, and temperature sensation. These genetic adaptations developed gradually over hundreds of thousands of years as their ancestors moved into colder environments.

The Woolly Mammoth coexisted with other mammoth species like the Columbian mammoth in North America, with DNA evidence showing hybridization between these species. Fossil evidence suggests these hybrid mammoths combined traits from both species, potentially giving them evolutionary advantages in certain environments. Early humans encountered these creatures, as evidenced by cave paintings and preserved remains found in permafrost, with some archaeological sites showing clear evidence of mammoth hunting and tool-making from mammoth bones.

Mammoth social structure appears to have been similar to modern elephants, with matriarchal herds consisting of related females and their young. Males likely lived solitary lives or formed temporary bachelor groups. Trackway evidence from fossil sites suggests herd sizes could range from 5-15 individuals, with larger aggregations possibly forming during seasonal migrations or at particularly rich feeding grounds.

Woolly mammoths developed remarkable adaptations for surviving in frigid environments that went far beyond their iconic shaggy appearance:

• Thick fur coat: Consisting of long guard hairs (up to 90cm) and dense underwool (5cm thick), with approximately 600,000 hairs per square meter
• Small ears and tail: Reduced surface area minimized heat loss, with ears only 1/3 the size of African elephants
• Fat reserves: A layer of fat up to 10 cm thick beneath the skin, with additional fat stores in distinctive shoulder and neck humps
• Specialized trunk: Featuring two finger-like projections at the tip (compared to one in Asian elephants) for precise grasping of vegetation
• Curved tusks: Some reaching 4 meters in length, used for digging through snow, stripping bark, and possibly display

The mammoth's teeth were particularly adapted to their abrasive diet. They had up to six sets of molars throughout their lifetime, with each new set being larger and more complex than the last. The final set could weigh over 2kg each, with up to 26 enamel ridges perfect for grinding tough grasses. Wear patterns on fossil teeth suggest a lifespan similar to modern elephants - about 60 years in the wild.

Their circulatory system included specialized blood vessels that helped regulate body temperature. A rete mirabile (wonderful net) of arteries and veins in their extremities acted as a heat exchanger, preventing excessive heat loss while maintaining tissue viability in freezing conditions.

Remarkable woolly mammoth specimens have been discovered in permafrost, providing unprecedented insights into their biology and ecology:

• Lyuba (2007): This 42,000-year-old baby mammoth found in Russia is the most complete specimen ever found, with intact internal organs and even milk in her stomach. CT scans revealed she died by suffocation in mud, preserving extraordinary details of her anatomy.
• Yuka (2010): Discovered in Siberia with intact soft tissue and brain matter, this young mammoth showed evidence of human interaction, with cut marks suggesting early humans may have butchered the carcass. Her preserved trunk was particularly significant, showing the detailed structure of the finger-like projections.
• Berezovka Mammoth (1900): Found in Siberia with stomach contents revealing its last meal of grasses, sedges, and buttercups. The position of this specimen suggested it died suddenly, possibly by falling into a crevasse while grazing.
• Jarkov Mammoth (1997): Excavated from the Taymyr Peninsula as a 23-ton block of frozen soil containing the complete mammoth. This recovery operation provided crucial information about mammoth environment and taphonomy.

These frozen specimens have allowed scientists to study aspects of mammoth biology that are rarely preserved in the fossil record. Analysis of stomach contents and coprolites (fossil dung) has revealed detailed information about their diet and digestive systems. Preserved skin and hair have shown the structure and coloration of their coat, while muscle tissue has provided insights into their physiology and potential mobility.

Recent discoveries in the North Sea, where lowered sea levels during glacial periods exposed vast areas now underwater, have yielded hundreds of mammoth remains. These "Doggerland" mammoths show interesting variations in size and morphology, suggesting this was an important refugium during periods of climate change.

The Irish Elk (Megaloceros giganteus) was one of the largest deer species to ever exist, despite its name it was neither exclusively Irish nor a true elk. This magnificent creature roamed across Europe, northern Asia, and northern Africa during the Pleistocene epoch.

First scientifically described in 1695 from remains found in Ireland, the Irish Elk is most famous for its enormous antlers, which could span up to 3.65 meters (12 feet) from tip to tip. These antlers represent the largest known antlers of any deer species, living or extinct.

Contrary to early evolutionary theories suggesting their antlers led to extinction, modern research indicates the Irish Elk was well-adapted to its environment, with antler size proportional to its massive body size.

The Irish Elk was an impressive specimen with several notable features:

• Size: Stood about 2 meters (6.5 feet) tall at the shoulders
• Weight: Estimated 450-700 kg (990-1,540 lbs) for males, females about 80% of male size
• Antlers: Massive palmate antlers spanning up to 3.65 meters, weighing up to 40 kg
• Body: Robust skeleton with concave frontals and thickened skull bones
• Coloration: Based on cave paintings, likely had light coloration with dark markings

The antlers were likely used for display and combat during mating seasons, similar to modern deer species. Their large size may have been driven by sexual selection.

The Irish Elk is well-represented in the fossil record, particularly in Ireland where numerous complete skeletons have been recovered from peat bogs. Notable finds include:

• Dunleer Specimen: The holotype specimen with exceptionally large antlers
• Barmeath Castle Collection: Contains the original described specimen
• National Museum of Ireland: Houses 10 complete skeletons and over 400 partial remains
• Siberian Finds: Some of the youngest known specimens from western Asia

These fossils have provided crucial insights into the biology and evolution of this magnificent species.

The Mexican Grizzly Bear (Ursus arctos nelsoni) was a distinctive subspecies of brown bear that inhabited the northern regions of Mexico and the southwestern United States. Known locally as "el oso plateado" (the silver bear), this magnificent predator was declared extinct in 1964.

First described scientifically in 1918 by Edward W. Nelson, the Mexican Grizzly was smaller than its northern relatives but still represented one of the largest land mammals in Mexico. Its silver-tipped fur gave it a distinctive appearance that set it apart from other brown bear subspecies.

The last confirmed sighting occurred in 1960, and despite occasional unverified reports since then, the species is considered extinct due to relentless persecution and habitat loss.

The Mexican Grizzly Bear possessed several distinctive physical traits:

• Size: Smaller than northern grizzlies, standing about 1.5 meters (5 feet) at the shoulder
• Weight: Typically 270-320 kg (600-700 lbs), with some larger specimens reported
• Fur: Silver-tipped brown guard hairs with a lighter undercoat
• Build: Powerful limbs with long claws adapted for digging
• Head: Characteristic grizzly profile with dished face and muscular hump

Their smaller size compared to northern grizzlies may have been an adaptation to the warmer climate and different food availability in their range.