CLOCK
To evolve from apes 7 hrs
Homo Sapiens so far 10mins
Human history 30secs
1000 years 3secs
I year 3msec
Diversity of SPECIES
An extraordinary diversity of species has evolved over 500 M years. From the earliest days, classification has been used to group and organize them as step towards understanding how evolution progressed. Initially skeleton features were the primary organizers, then habitat and food, more recently DNA has been used.
A species is a subset of animals that can interbreed. Similar species are grouped into "Genus" and so forth back to "Life", which consists of Cellular Life; Bacteria, Eukaryota, and non cellular life; viruses etc. Eukaryota cells contain full genetic function, and led to todays diversity.
The "Phyogenetic tree" is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time. In other words, it is a branching diagram or a tree showing the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics. The first attempt to lay out evolutionary history as a progression based on anatomy was Ernst Haeckel's Biogenetic Law (1866). His tree "Pedigree of Man" had the correct sequence of Primitive - Invertebrate - Vertebrate - Mammals.
A simplified classification covering the most common animal types is;
Bacteria- Single celled with a circle of DNA
Bacillati aerobic - Cyanobacteria that form Stromatolite residues
Archaea
Extremophile
Methanogens - methane metabolite
Halophilic - high salt inhabitants
Hyperthermophilic - hot vent inhabitants e.g. in Yellowstone pools
Eukaryotes - cells with a nucleus, genetic propagation, aerobic metabolism
Algae
Phyto-Plankton - photosynthesis
single cell
macro multi celled e.g. Kelp
Diatoms - hydrated SiO2 cell wall
Plants - Cellulose (glucose polyester) structure & photosynthesis
Fungi - Chitin (amino-glucose polyester) shells & Krebs cycle digestion eg. Yeast
Sponges - multicell filter feeders, endoskeleton of CaCO3
Cnidaria
Jellyfish
Corals - CaCO3 exoskeleton
Bilateria
Echinoderms - endoskeleton of CaCO3
Sea Urchins
Chordata
Mollusks
Bivalves - CaCO3 exoskeleton.
Cephalopods -
Arthropods - Chitin exoskeletons,
Trilobites
Burgess Shale uniques
Crustaceans
Insects
Vertebrates - internal CaPO4 skeletons for uninterrupted growth
Fish
Amphibians -
Reptiles -
Dinosaurs -
Birds -
Mammals -
Around 450 million years ago, the first land plants appeared, with Chlorophyll for trapping light and Cellulose (a polysaccharide or natural polyester) for superstructure. Around 420 million years ago, club mosses, ferns then appear. By the end of the 363 My ago, most of the basic features of plants today were present, including roots, leaves and secondary wood in trees. The 358-298 My ago saw the development of forests in swampy environments dominated by clubmosses and horsetails, including some as large as trees, and the appearance of early gymnosperms, the first seed plants. In the time of the dinosaurs the world was covered by a hardy conifer forest, providing accessible food for very large herbivores. By the end of the Cretaceous 66 million years ago, over 50% of today's flowering plants "angiosperm" had evolved, accounting for 70% of global species. It was around this time that flowering trees became dominant over conifers, providing a new high calorie niche ready and waiting for the primates. 20 million years ago, grasslands took over from trees as the climate cooled and dried out providing a new niche for ruminants, the grass digesting herbivores, and their predators.
The genetic line leading to Fungi developed from eukayotes that could decompose protiens for energy around 1B years ago. Fungi, are the clean up crew as decomposers of protein and cellulose. The users of oxygen starts with sponges which evolved as fixed growths in the water that filtered nutrients from the flowing water. The genetic thread splits into the Bilatria with symmetrical eyes and limbs, and Cnidaria are predatory marine invertebrates including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites. Corals are the most spectacular subgroup with Calcium carbonate superstructure. Although some corals are able to catch plankton and small fish using stinging cells on their tentacles, most corals obtain the majority of their energy and nutrients from photosynthetic algae that live within their tissues. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. The shapes of the skeleton is thought to have evolved to trap nutrients and colonizers depending on the local flow patterns. A coral "group" is a colony of very many genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, when mature, settles to form a new colony. The different shapes result from combinations of 3 different calcium carbonate crystal structures, with different symmetries.
The Bilateria genetic thread led to mollusks, insects and eventually mammals. Around 610 My ago, the Protostomes appeared who developed mouth before anus in the embryo. Around 550 My ago, there was the first great explosion of species in water, including Arthropods that became crustations such as krill, shrimp, lobster and crabs, Mollusks, and Fish. The Arthropods had a jointed exoskeleton such as centipedes, millipedes, scorpions, spiders, woodlice, mites, and ticks, 6 legged insects and crustaceans.
Another branch led to mollusks and Cephalopods such as Squid and Octopus. Cameroceras with a 2m shell is an early cephalopod from 450 Mya. The Mollusks appeared with an shell and a whole body circulation of oxygen using "Hemolymph" and copper based blood. The snails evolved into squids and octopus with closed circulation of a copper containing blood, which enables oxygen to be delivered to key organs. Nautilus, early Cephalods, are remarkable as the first examples of a species with pinhole camera eyes.
Without a skeleton, octopus has very limited evolutionary options as a predator or for defense, Becoming a smarter is the option leading to camo and clever hiding.
Octopus blood is copper-based (hemocyanin), which turns it blue and helps it bind oxygen efficiently in cold, low-oxygen water. But it’s thicker than human blood, making it hard to pump. To manage this, octopuses evolved three hearts. Two branchial hearts oxygenate the blood at the gills, while a third circulates it through the body. When the octopus swims, it shuts off the branchial hearts to reduce workload — making swimming tiring. This is why they prefer crawling.
The octopus only have one cycle of reproduction in their lives. The female protects their eggs as they develop, one of the hallmarks of higher intelligence. Octopuses, like other coleoid cephalopods but unlike more basal cephalopods or other molluscs, are capable of greater RNA editing, changing the nucleic acid sequence of the primary transcript of RNA molecules, than any other organisms. Editing is concentrated in the nervous system, and affects proteins involved in neural excitability and neuronal morphology. More than 60% of RNA transcripts for coleoid brains are recoded by editing, compared to less than 1% for a human or fruit fly. Coleoids rely mostly on ADAR enzymes for RNA editing, which requires large double-stranded RNA structures to flank the editing sites. Both the structures and editing sites are conserved in the coleoid genome and the mutation rates for the sites are severely hampered. Hence, greater transcriptome plasticity has come at the cost of slower genome evolution. In addition, the octopus evolved a genome as complex as humans with "jumping genes". In these, the DNA is 45% transposed (reorganized within the animal) a feature that has been linked to intelligence in humans. The octopus has demonstrated remarkable intelligence in problem solving and ability to self camouflage in color and texture. The octopus seems be a real "alien" intelligence on this planet with completely different design, and biochemistry. What they found was a brain more complex than that of a rat or a mouse. In fact, its complexity was similar to that of a dog’s brain. Some cephalopods have more than 500 million neurons. In comparison, the resourceful rat has 200 million, and the ordinary mollusk has 20,000. Their brain-to-body-mass ratio falls between that of cold and warm blooded vertebrates. They demonstrate tool use, recognition of humans, the ability to solve abstract problems for instance; captive cephalopods have also been known to climb out of their aquaria, maneuver a distance of the lab floor, enter another aquarium to feed on captive crabs, and return to their own aquarium. They can unscrew the lids of bottles from the inside. These suggest an intelligence superior to dogs, on a par with primates.
The remarkable capability of the Octopus probably results from the fact that Cephalods have retained more or less the same physical layout for over 450M years. All their evolutionary changes have been channeled into intelligence, camouflage, dexterity.
Insects and crustaceans have exoskeletons of amino-polysaccharides for superstructure. There were no land based creatures so a huge niche was empty. The insects evolved from crustations as pollinators of the plants that appeared around 400 M years ago. Insects took over and ruled the land until the amphibians showed up. Today, they probably represent 90% of the species on earth. They show some amazing collective capabilities. Butterfly's evolved around 50 M years ago post KT extinction. Butterflies have the unique migration from Mexico to Alaska, travelling north over 4-5 generations each lasting 2 months using the sun as a guide, following the flowering of milkweed. They then fly south in a single 8 month generation. Bees have developed signals to show each other the direction to food. Ants are herbivores that demonstrate large scale communication and cooperative action.
https://www.nationalgeographic.com/animals/article/monarch-butterfly-migration
In the ocean, lampreys were the first to evolve a closed circulation system with iron containing blood - hemoglobin. This enables oxygen to be delivered to key organs.
The vertebrates first appeared with lobe finned fish such as lungfish and celeocanth, as part of the Cambrian explosion 530 M years ago. In the Devonian 445 M years ago or the "age of fishes" ray finned fish (bony vertebrates) became easily the largest class of fish. This extinction event coincides with the recovery from ice age associated with the Appalachian uplift and falling CO2 levels . Cartiliginious include sharks and rays. The sharks evolved keeping their eggs inside their bodies until they hatched to protect their young. Fish have a 2 chamber (atrium & ventricle) heart.
Vertebrates use polypeptides (natural polyamides) for superstructure, skin etc. Bones are mainly regarded as rich in minerals such as calcium and phosphorus and collagen proteins, but some special carbohydrate and lipids are also found. The structure of the Ca–P solid phase in bone was first identified by deJong in 1926 as a crystalline calcium phosphate similar to geological apatite by chemical analyses and, most importantly, by X-ray diffraction
There are 48 orders of fish, covering examples from a wide range of habitats include;
Cypriniformes: 4644 fresh water insectivore & herbivore - Carp, goldfish, minnows -
Siluriformes: fresh water boney fish carnivores - Catfish -
Characiformes: fresh water carnivores - Piranha -
Salmoniformes; sea & fresh water carnivores - Char, Salmon, trout -
Gobiiformes: amphibious - Mudskipper -
Scorpaeniformes: kelp edge feeders - rockfish, lionfish, sculpines
Carangiformes: bottom feeders - flounder, plaice, sole, also marlin, swordfish.
Gadidiformes: shallow sea carnivores - Cod, Haddock
Clupeiformes: - ray-finned boney forage and food fish - herring, anchovy sardines.
Scombriformes: deep sea carnivores - Tuna, mackerel -
Ophidiiformes: deep water eels - Cusk-eel -
Perciformes: colorful reef boney fish - Wrasse, parrotfish, snapper, angelfish, chilean seabass, redfish -
The best eating are the 2nd level carnivores. Cave fish are specially adapted members of many fresh water orders.
Osteichthyes or "Ray Finned Bony Fish" ; most common with 28,000 species in 12 orders, including a huge variety of body styles.
Perciformes 10,000 species - Wrasse, parrotfish, snapper, angelfish, perch - colorful reef fish
Lophiiformes: commonly called “anglerfishes” - deep water fish
Gasterosteiformes: soft fin rays - sea horses
Amiiformes: - Bowfin - inhabit swampy waters of bays of warm lakes and rivers
Tetraodontiformes: odd shaped coral dwellers- pufferfish, box fish, sunfish
Siluriformes - Catfish - fresh water predators
Scorpaeniformes: Scorpionfish - cheeks are crossed by a bony plate -
Lepisosteiformes: an elongated “bill” - Gar
Elopiformes: primitive fishes - Ladyfish, bonefish
Batrachoidiformes - Toad fish - as it looks
Anguilliformes - eels or morays
Clupeiformes: - Sardines, anchovy - very small, marine fish
https://osteichthyesbiology11.weebly.com/orders-within-class-osteichthyes.html
The first major groups of amphibians developed at the end of the Devonian period, around 370 million years ago, from lobe-finned fish which were similar to the modern coelacanth and lungfish. This is coincident with the recovery from the ice age extinction event thought to triggered by the explosion of plant life and falling CO2. The amphibians, such as frogs, marked the transition onto land, while needing water for reproduction and their young. The amniotes evolved hard shelled eggs that no longer needed water emersion to develop. This lead them to spread all over Pangea. After the Carboniferous rainforest collapse 305M years ago, amphibian dominance gave way to reptiles, and amphibians. Fauna moving to the land was the second great species explosion.
Amphibians have a skeletal system that is structurally homologous to other tetrapods, though with a number of variations. They all have four limbs except for the legless caecilians and a few species of salamander with reduced or no limbs. The bones are hollow and lightweight. The musculoskeletal system is strong to enable it to support the head and body. The bones are fully ossified and the vertebrae interlock with each other by means of overlapping processes. In most amphibians, there are four digits on the fore foot and five on the hind foot, but no claws on either. They have lungs and a heart that consists of a single ventricle and two atria. Today Frogs and Salamanders are the most commonly found.
The origin of the reptiles lies about 310–320 million years ago, in the steaming swamps of the late Carboniferous period. The reptiles split into 2 genetic threads; one led to to todays reptiles and birds via the dinosaurs.
The first branch are called the sauropsids, led to dinosaurs and reptiles that are around today; Lizards, Snakes, Iguanas, and lastly Turtles, and Crocodiles. Along with lungs, the first 4 chamber heart appears in the reptile line, separating blood supply to the lungs and everything else. The second branch are the synapsids, Lystrosaurus was a key survivor until finished off by the dinosaurs who simply grew larger, and the branch has no reptile survivors today but eventually evolved to mammals.
In the mid to late Triassic, the dinosaurs evolved from one group of archosaurs, and went on to dominate terrestrial ecosystems during the Jurassic and Cretaceous. It appears that reptiles that were self sufficient straight out of the egg continued to grow through life, whereas proto mammals have increased fetal development followed by limited adult growth. This "Triassic Takeover" may have contributed to the evolution of mammals by forcing the surviving mammal successors to live as small, burrowing, mainly nocturnal insectivores.; nocturnal life probably forced at least the proto-mammals to develop fur, better hearing and higher metabolic rates.
Archosaurs/ Sauropsids also experienced an increase in metabolic rates over time during the Early Triassic. They likely originated in the low-latitude regions of Gondwana near the equator, an area that today includes northern South America and northern Africa. The earliest-known dinosaur fossils date to roughly 230 million years ago, including Eoraptor and Herrerasaurus from Argentina, Saturnalia from southern Brazil and Mbiresaurus from Zimbabwe. While sharing certain traits defining them as dinosaurs, they had sufficient differences that suggest millions of years of dinosaur evolution had already occurred.
https://www.yahoo.com/news/where-did-dinosaurs-first-evolve-164423292.html
Dinosaurs originated in a part of Pangea that is now South America, diverging into Saurischians which include Therapods (Trex and birds), Sauropods (huge long necked)., and the Ornithischians which include a range of herbivores Back Armored, Duck Billed, Horned (Triceratops) They dispersed more than 220 million years ago across parts of Pangea that later became separate continents.
https://www.eurekalert.org/news-releases/771395
The dinosaur era lasted 200M years and was the cradle of most of todays species.
Some dinosaurs probably raised their young rather than just abandoning. Maiasaura (Late Cretaceous herbivore) individuals were found tangled together, in different stages of development. But further analysis demonstrated that newly hatched Maiasaura possessed immature leg muscles (and thus were probably incapable of walking, much less running), and their teeth had evidence of wear. What this implies is that adult Maiasaura brought food back to the nest and cared for their hatchlings until they were old enough to fend for themselves — the first clear evidence of dinosaur child-rearing behavior.
https://www.thoughtco.com/were-dinosaurs-good-parents-1091906
Structural differences that led to modern birds "Ichthyornis", are seen in light hollow bones. wing articulation and a large keel sternum to anchor flapping muscles.:
https://royalsocietypublishing.org/doi/10.1098/rsbl.2024.0500
The feathered birds evolved from warm blooded dinosaurs around 160 M years ago, the first is Anchiornis with large brains and a closest relative to the Velociraptor. Dinofuzz appeared 125Mya, feathers on microraptors 112Mya, fully functional birds with hollow bones (eg Archiopterix) 90Mya. Small ground welling omnivore birds were the only survivors along with underground mammals of the KT meteor. “It seems like birds had happened upon a very successful new body plan and new type of ecology—flying at small size—and this led to an evolutionary explosion,” when the niches opened up after the K/T meteor.
https://www.scientificamerican.com/article/how-dinosaurs-shrank-and-became-birds/
One way to group survivors of the K/T meteor are collectively "Neomithes"; BOP, flightless, water birds, land birds, small perching songbirds. A more formal classification includes:
Palaeognathae (ratites such as ostriches etc) Flightless
Galloanserae (ducks, chickens etc). Dom. game Neonaves
Mirandornithes (flamingos and grebes) Early water
Columbimorphae (mesites, sandgrouse and pigeons) Wild game
Otidimorphae (turacos, bustards and cuckoos) Brood parasite
Strisores (nightjars, swifts, hummingbirds and allies) Frantic flyers
Gruiformes (cranes and rails) Waters edge
Eurypygimorphae (sunbittern, kagu and tropicbirds) Flashy
Pelicani (pelicans, herons, ibis, cormorant, penguin, loon) Big seabirds
Acciptermorphae (owls, eagles, vultures) BOP
Coaracilmorphae (bee-eaters, woodpeckers, hornbills, roller) Big beaked
Passerimorphae (falcons, parrots) Perching
Tyranni (non-singing, Americas - broadbills, flycatchers),
Passeri (songbirds - finch, crow, wren, flycatchers, tanagers, sparrows, cardinal, grossbeak, starlings, weavers, warblers),
The foot of a passerine has three toes directed forward and one toe directed backward for perching. Grosbeak are various species of seed-eating passerine birds with large beaks. Some are finches, while others are cardinals; one is a member of the weaver family.
Owls are particularly interesting specialists, close to eagles and vultures as shown by their narrow skulls and well defined beak. The owls have particularly large eye sockets that give them exceptional vison. The eye balls are so large there is no room for muscles to direct their eyes, hence their characteristic head bobbing to enhance 3D vision. The large flat "face" is a web of feathers that create a sounding board for enhanced highly directional listening.
Climate change is affecting bird populations.
Today's reptiles are grouped into "shelled" turtles, and vertibrate crocodiles, lizards, iguanas, and snakes.
In the proto-mammal genetic thread, the monotremes were the first mammals who laid eggs but suckled their young extending the time before a fully functioning digestive system needed. The duck billed platypus is the best known. DNA evidence supports a South American origin for marsupials, with Australian marsupials arising from a single Gondwanan migration of marsupials from South America, across Antarctica, to Australia, 100-120 My ago. The Marsupials thrived in Australia, Wallacea and the Americas now include kangaroos, koalas, Tasmanian devils, wombats, wallabies, possum and bandicoots. The Opossum is a close relative, a marsupial that originated in S America, and now live in N America.
By 70 My ago (Creataceous), the continents had started to move apart, Africa, S. America, Australia, Antarctica all separate. N America was the home of the widest variety of dinosaurs, with a land bridge to the other continents. Dominant dinosaur predators blocked any chance for the mammals, birds and reptiles to thrive.
The KT meteor impact 65 My ago produced a combination of blast, tsunami, firestorm from re-entering impact debris, dust that blocked the sun for years and acidified the oceans. As a result, there was a mass extinction of anything over 50 lbs which included all large herbivore and their predator carnivore dinosaurs, presumably the little guys could hide underground. Marine invertebrates were also decimated. In these new uninhabited niches new species of mammals, reptiles, and birds had a better chance of survival. After the extinction, different species were localized in Africa (Elephants etc), S. America (Sloths etc), Laurasia (Rodents, Ungulates and Primates).
https://www.britannica.com/science/K-T-extinction
Over the next 65 M years, plate tectonics created all the young mountain features such as Himalayas, Alps, and Rockies which were eroded back creating new ecological niches filled by new mammal and bird species. The humans evolved over the last 7M years with volcanic activity and ice ages creating another set of niches for species to thrive.
True placental mammals (the crown group including all modern placentals) arose from stem-group members of the clade Eutheria, which had existed since at least the Middle Jurassic period, about 170 mya. These early eutherians were small, nocturnal insect eaters, with adaptations for life in trees.[5]. Eutheria also called Pan-Placentalia, is the clade consisting of placental mammals and all therian mammals that are more closely related to placentals than to marsupials.
The first placental mammals were shrew - like who lived underground, a niche that was inaccessible to cold blooded reptiles, and were small enough to be ignored by the dinosaurs. To this point all species of animals used eggs for reproduction with a limited energy supply before the fetus had to be viable. The placenta allowed much longer time for the fetus to develop with unlimited energy supply. Brain expansion and increased neuronal number are hallmarks of cortical evolution, particularly in humans. A new study establishes a link between the length of gestation, neurogenesis, the maternal environment, and key features associated with more complex brains. https://www.cell.com/current-biology/fulltext/S0960-9822(20)31288
Starting from the shrews, a huge range of new mammal herbivores and their predator carnivores evolved rapidly to replace the dinosaurs that had dominated over the land. The huge variety evolved to fit different climate, food, and competitor niches. Mammals also returned back to the water evolving into hippos and eventually marine mammals such as whales, a relation confirmed by DNA. Marine mammals have a up down spinal motion like galloping mammals another indication of their land mammal ancestors. This is a contrast to reptiles such as crocodiles and snakes retain the side to side spinal motion as they move just like fish.
Mammals DNA subdivide into:
-
Primates - Monkeys, Apes, Humans
-
Rodents - Mouse, Rabbits, Capybara, Beaver, Nutria, Squirrels
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Herbivores - Megacerops evolved into Horses, Deer, Giraffes, Rhinos and Hippos which are the nearest land relatives to Cetaceans such as Whales & Dolphins.
-
Predators "Carnivorae" - Cats including civets, dogs, hyenas, Racoons, Coatis, Otters, Pinnipeds such as seals.
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"Xenarthra" Insect eaters - Sloths, Anteaters, Hedgehogs, Armadillos
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"Afrotheria" Trunked - Elephants, Aardvark, Elephant Screw, Hyrax, Dudong (Manatee or sea cow).
There are key bone signatures of species. There is a large vertical fin on the vertebrae of quadrupedal walking mammals that anchors the big muscles that support galloping . There is a bone dome behind the ears of whales that hear underwater. Pelvis shape and hip socket show if the animal is quad or bi-pedal. Tooth shape indicate the preferred food. Ungulate herbivores have hooves. Ruminants have multiple stomachs who thrived on the grass that replaced forest 20 M years ago as the earth cooled and dried.
Whales are closest to Hippos, and evolved into the ocean around 50 Mya as Pakicetus, a wolf sized and walking mammal with water living adaptations but also multiple stomachs as in ruminants. In contrast, pinnepeds such as seals are Carnivora with racoons as closest relatives.
Rodents and primates diverged 80-55 My ago, 53 My ago is the date of the earliest primate fossil. There is a very patchy fossil record for early primates. The first primate-like mammals are referred to as proto-primates. They were roughly similar to squirrels and tree shrews in size and appearance. The existing fossil evidence (mostly from North Africa) is very fragmented. These proto-primates remain largely mysterious creatures until more fossil evidence becomes available. Although genetic evidence suggests that primates diverged from other mammals about 85 Mya.
Primates are adapted for tree climbing; 1) a rotating shoulder joint, 2) a big toe that is widely separated from the other toes and thumbs, which are widely separated from fingers (except humans), which allow for gripping branches, 3) stereoscopic vision, two overlapping fields of vision from the eyes, which allows for the perception of depth and gauging distance. Other characteristics of primates are brains that are larger than those of most other mammals, claws that have been modified into flattened nails, typically only one offspring per pregnancy, and a trend toward holding the body upright.
https://open.lib.umn.edu/humanbiology/chapter/1-7-the-evolution-of-primates/
The first true primates date to about 55 MYA. They were found in North America, Europe, Asia, and Africa. As the climate cooled, tropical forests and their occupants were pushed down to the tropics. Fruiting trees that emerged after the KT extinction provided a new niche with high calorie food for tree dwellers, that is filled by the primates. It helped that primates are really the only tree based predators for other primates. These early primates resembled present-day prosimians such as lemurs. Evolutionary changes continued in these early primates, with larger brains and eyes, and smaller muzzles being the trend. By the end of the Eocene epoch, many of the early prosimian species went extinct due either to cooler temperatures or competition from the first monkeys.
https://pressbooks.umn.edu/introbio/chapter/humansevolution
Many mammal species monkeys, bears, cats, large herbivores are common to both S America and Africa however they evolved after KT event 65M years ago long AFTER the tectonic split 120M years ago. Apes evolved around 25M years ago. Therefore there must have been a much later path but before 25M. Around 50M years ago, temperatures were +8C from today, heavily forested, with no land ice and sea levels 100m higher. The consensus view is that most were "lucky arrivals" from a combination of island hopping in the north and riding vegetation rafts. The accepted view is that Madagascar, Galapagos and other islands were also populated using rafts.
https://dcpaleo.org/south-american-fossil-mammals
Compared to rodents, the primates are much larger tree dwellers, with all sorts of enabling adaptations such as grip, strength, and prehensile tails. As large tree dwellers they were safe from most predators. There was little competition for high calorie food. The result was they thrived and developed much larger brains.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185448/
https://en.wikipedia.org/wiki/Old_World_monkey
Early Primates - mostly nocturnal and very small
Lemurs in Madagascar,
Tarsiers SE Asia Islands,
Loris in SE Asia,
Galagos or Bushbabies in Africa
Monkeys - tails, walking through trees;
Macaques including Rhesus & Japanese, Proboscis, Langur (India) in Asia
Baboons, Ververt, Colobus, Mandrill, Gelada (Ethiopia) in Africa
Howler, Squirrel, Tamarin, Capuchin, Marmoset in S America with prehensile tails
Apes - no tails, swinging through trees;
Gibbons in Asia
Orangutans in Asia
Gorillas in Africa
Chimpanzees, Bonobos in Africa
Humans in Africa
N and S America were connected only 3M years ago accounting for the species differences between them. Around 200 K years ago humans appeared and are now for better or worse are the dominant species.
A species of primate "Giantopithecus blacki" grew to 10 ft tall ! but went extinct 250,000 years ago during a period of grassland domination possibly due to the loss access to fruit. Closely related to Orangutans,
Many more animals in South America have prehensile tails than in Africa and Southeast Asia. It has been argued that animals with prehensile tails are more common in South America because the forest there is denser than in Africa or Southeast Asia.[3] In contrast, less dense forests such as in Southeast Asia have been observed to have more abundant gliding animals such as colugos or flying snakes; few gliding vertebrates are found in South America. South American rainforests also differ by having more lianas, as there are fewer large animals to eat them than in Africa and Asia; the presence of lianas may aid climbers but obstruct gliders.[4] Curiously, Australia-New Guinea contains many mammals with prehensile tails and also many mammals which can glide; in fact, all Australian mammalian gliders have tails that are prehensile to an extent.
During the early Miocene, 23.03 to 5.333 million years ago, a wave of mammalian immigration from Eurasia over the Bering land bridge brought bear-dogs (early ancestors of modern canines of the genus Amphicyon), European rhinoceroses, weasels, and a variety of deerlike mammals to North America. Also during this time, mastodons escaped from their isolation in Africa and reached North America by the middle of the Miocene
Many large animals disappeared 13–11,000 years ago, "Quaternary extinction event", possibly due to climate, habitat and sea level change (120m LOWER) at the end of the last ice age, or human predation as communities get established. In North America the last camel vanished along with horses, short-faced bears, mammoths and mastodons, ground and unicorn sloths, sabertooth cats, and many other megafauna. In New Zealand the arrival of the Polynesians led to the extinction of the Dodo and other flightless birds.
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