What was the first mammal on earth?
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From wikipedia\nMost early mammals were tiny shrew-like animals that fed on insects. However, in January 2005, the journal Nature reported the discovery of two 130 million year old fossils of Repenomamus, one more than a meter in length, the other having remains of a baby dinosaur in its stomach (Nature, Jan. 15, 2005 [1]). The earliest mammals include:\n\nEozostrodon: Triassic and Jurassic \nDeltatheridium: Cretaceous \nJeholodens: mid-Cretaceous \nMegazostrodon: late Triassic and early Jurassic \nTriconodont: Triassic to Cretaceous \nZalambdalestes: late Cretaceous \nAlthough mammals existed alongside the dinosaurs, mammals only began to dominate after the mass extinction of the dinosaurs 65 mya, in the Cenozoic.
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The largest animal on Earth is the blue whale (Balaenoptera musculus). Newborn calves are 6-8 m (20-26 ft) long and weigh up to 3 tonnes (2.95 tons). An adult whale can grow to a length of 35 m (115 ft) and weigh up to 130 tonnes.\n\nA female weighing 190 tonnes and measuring 27.6 m (90 ft 6 in) in length was caught on March 20, 1947. An even bigger 33.58-m (110-ft 28-in) long female landed in 1909 at Grytviken, South Georgia in the South Atlantic.
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The very oldest species on Earth are the cyanobacteria, which seem to have been around virtually unchanged for nearly 4 billion years. This is based on fossils of that age that have been compared under high-powered microscopes to existing species of these bacteria. Other bacteria that are about as old are the archaea, which thrive in acidic, high- temperature, or high-radiation environments. \n\nAnother remnant of ancient organisms includes the stromatolites, mounds of algae and bacteria that today grow in the Bahamas, Shark's Bay Australia, and a few other limited environments. They have been around, also largely unchanged, for over 3 billion years and at one time were the Earth's dominant form of life. \n\nOn the animal side of things, the brachiopod Lingulaa is probably the oldest, having existed nearly unchanged for over 500 million years, and the horseshoe crab (limulus) has been on the planet for several hundred million years, too. Since the average "lifespan" of a species is only a few million years, having such ancient species around is very impressive. \n\nA good book about the earliest life is "Cradle of Life" by J. William Schopf. He is one of the premier scientists doing this sort of research. At a more advanced level, he has edited two scientific books, "Earth's Earliest Biosphere" and "The Proterozoic Biosphere", which should be in your university's geology or science library.
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the earliest known form of life is cyanobacteria which grew in bluish green pod like colonies approximately 3.4 billion years ago.
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Placentarian mammals do (not the platypus or equidna)
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The whale. It is indeed a mammal.
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The earth is 4.6 billion years old. The sun is close to 5 billion. Liquid water did not exist on earth until about 4 billion years ago. Life seems to have appeared 3.8 billion years ago. By 3.5 billion years ago, we have fossilized stromalites which are IDENTICAL to the ones still made today by prokayote blue-green algae in the Indian ocean.\n\nThe first eukaryote organisms (with cells structures like ours) first show up 1 billion years ago. Within 500 millions years from then, complex forms can be found in the fossil record which are ancestral to modern lineages. But here are NO fish, amphibians, reptiles, mammals or birds. These all arise later in sequence by evolutionary modification as the fossil record clearly shows.\n\nThe bottom line is that only evolution provides a comprehensive argument that explains what we see in the fossil record. The Intelligent Design people are frauds who misrepresent the data and are no more credible that the Gish/Morris combine of liars that plaugued us in the 70s and 80s.\n\nI (Dr. Art Sippo) am a 53 year old cradle Catholic with a BS in Chemistry (Magna cum laude)from St. Peter's College, an MD from Vanderbilt University, and a Masters in Public Health from Johns Hopkins. After Catholic apologetics, paleontology is my favorite hobby. I have been studying it since I was a kid in the 1950s.\n\nWith regard to "macroevolution" that term is actually passe. It is still touted by Creationoids so that they can say they support microevolution but not macroevolution. These terms were used around 30 years ago before the discovery of the complexity of eukaryote genetics. Microevolution was what happened when there were single alterations either in DNA sequences or protein sequences due to mutations. There were other mechanisms that worked in bacteria (eg., conjugation, plasmids) but their utility in eukaryotes was questionable. At that time it was assumed that prokaryote (eg, bacterial) genetics was directly applicable to eukaryotes (eg, mammals). We now know that this is not so.\n\nEukaryote genetics is so complicated that it has not been fully elucidated. There is modification of the transcription of DNA to messenger RNA, a further cropping of m-RNA into introns and extrons, and further modification of the proteins for which they code. None of this happens in prokaryotes.\n\nAlso eukaryotes use a "homeo box" generalized assembly kit which is functionally identical in all lineages and which can with slight tweaks make large changes in how the genotype (DNA data) is expressed into a phenotype (external structure). \n\nAlso, eukaryotes use chromosomes which rearrange themselves spontaneously in several different ways. This helps to contribute to evolution in the absence of any DNA mutations.\n\nAll of these mechanisms -- and more -- contribute to evolution. In fact everything that is necessary for what had been called "macroevolution" is present in these more complex genetic systems.\n\nWith regard to the changes in species of higher animals, many Creationoids have said that there were large systematic gaps between major taxa. They are right, In the linnean system there are large SYSTEMatic gaps, but these gaps are due to the system of classification, and do not correspond to real biological differences. Linnaeus was a Creationoid. He thought that each species was distinctly made by God. So he created a complex classification system that emphasized distinctions and did not assume common descent. In reality, his classifications were merely man-made conventions that limped badly. For example, the Class Reptilia included not only lizards but snakes (some of which bear live young and don't lay eggs), turtles, crocodiles (that all have 4 chambered hearts), dinosaurs (some of which have feathers), ichthyosaurs, mososaurs, plesiosaurs, and pterosaurs (some of which have fur). The problem with fish is even more complex.\n\nIn many cases, an organism does not fit into the Li
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Seals evolved from some terrestrial animal because anatomical analysis shows a 5-digit fin.  It probably evolved from a bear or otter-like creature.   Many mammals spend the majority of their time in the ocean, and when feeding is more successful in the ocean than on land, aquatic adaptations derive.
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'Lucy' the first known hominid, came from Tanzania in Africa.
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Mankind did not land on Earth. Rather, we evolved from lifeforms already present on the Earth. Our evolutionary roots can be traced a few million years back and the species that most closely resembles us in terms of genetic makeup(which is also most probably the one from which we completed the final stage of evolution) is the chimpanzee.
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The planet earth is at least 4500 million years old. The earliest signs of life date back 3000 million years, and by 600 million years ago quite complex animals and plants existed. \nThe story of the backboned (vertebrate) animals - the fishes and other forms that eventually led to humans -began about 600 to 500 million years ago. The first definite fossil of a creature with a stiffening notochord along its back was a Cambrian animal called Pikaea, which was discovered in 560- million-year-old rocks in Canada. The oldest complete fish fossil so far found came from central Australia, and was a jawless, armoured fish called Arandaspis, which dates from the early Ordovician period. This small filter-feeding or mud- grubbing fish lived in shallow coastal waters over 480 million years ago.
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As pointed out whales are mammals, they give birth to live young and nurse them with mammary glands. Whales have flippers that evolved from hands and actually have the digital structure pretty much intact, some even have the remains of pelvises and non-functioning hind limbs, clear evidence of their terrestrial origin.\n\nIf your really interested talkorigins.org has a really interesting article on the subject, it's heady, but a good read.
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Well, on this Earth, primates are the ancestors of the only known sentient species.  I don't know that these means that humans are the 'best' species, even if we are (arguably) the most intelligent.\n\nIf the human evolutionary path is any indication, there may be some prerequisites for the development of sentience.  A large brain is the most obvious one, but things such as free and mobile appendages suitable for tool use may also be required.  As far as bats go, they are limited in the size that their brains can grow to and still be able to maintain flight.  Their forelimbs are also not readily available for manipulatory organs.  \n\nSo a sentient bat species would probably be unlikely.  The ecological niche of intelligent species would probably go to a different species that already displays some of these adaptations to some extent.\n\nMice are a remote possibility for potential sophonts.  They can achieve a semi-bipedal stance and use their forepaws for some remarkable manipulations.  Their current small size is their chief impediment.  Increasing body and brain size to an extent to make them candidates for sentience would also slow them down, remove their stealthiness and ability to fit into tight spaces, and many of the other adaptations that allow them to survive in a world full of predators.\n\nOther than the great apes, I think one of the major candidates for potential for sentience is the racoons.  They are already pretty smart, near the top of the food chain, versatile, adaptable, omnivorous, and curious, and have very well developed forepaws with perhaps the highest level of manual dexterity of any mammal outside the primates.  \n\nI seem to recall a novel by Stephen R. Boyett called 'The Architect of Sleep' in which a man goes to a parallel universe where racoons evolved sentience instead of the primates.  It seemed to be an aquel (a book that fails to spawn the expected series of sequels), but if I remember correctly it was quite intriguing.\n\nAnother intriguing species with curiosity, adaptability, intelligence and manipulative abilities that I think would make an interesting candidate for the development of sentience are some of the large cephalopods (like the giant Pacific octopus, Humboldt's squid or even the giant squid!!)  - imagine the society they might create.
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Nothing that was fully aquatic, but penguins, puffin relatives, fulmars, ducks, and many other sea birds would have evolved by then.\n\nIf you are referring to plesiosaurs, ichthyosaurs, etc., they weren't dinosaurs and were long extinct by the time mammoths came around.
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If you picked up a person from 2006 and dropped them into the primitive earth (4.55 billion years ago), I don't know what would kill them first. There was no oxygen. High levels of methane and ammonia. No ozone layer to protect from radiation. And I believe there were no land masses yet.
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Check out the Honey Badger, they are without doubt the hardest mammals on this planet. They were even listed in the guiness book of records as the most fearless. Check out the link.
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The mammals are the class of vertebrate animals characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; and endothermic or "warm-blooded" bodies. The brain regulates endothermic and circulatory systems, including a four-chambered heart. Mammals encompass some 5,500 species, distributed in about 1,200 genera, 152 families and up to 46 orders, though this varies with the classification scheme.\n\nPhylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals).