CLOCK
To evolve from apes 7 hrs
Homo Sapiens so far 10mins
Human history 30secs
1000 years 3secs
I year 3msec
Evolution of SPECIES
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.
We now have much more fossil history, biochemical information and DNA. A tree based on Mitochondrial DNA was recently compiled giving a more detailed view of relationships. The family tree drawing was inspired by a linear diagram of species differentiation in cytochrome C from a biochemistry textbook, Lehninger. Cytochrome C is a genetic protein common in all living things. The organic curved branches is humans centered but not at the top of the tree. Canines evolved with better smell, whales with bigger brains, and eagles with better vision.
https://scitechconnect.elsevier.com/africa-retracing-human-evolution-migration-dna
https://rsscience.com/the-biological-classification-of-paramecium-name-history-and-evolution/
Personal communication from Mark Hom MD
I annotated the evolution tree with the key functions of metabolism, energy distribution, structure and reproduction, that enabled the different branches. Life started with cyanobacteria (plankton) and plants that use photosynthesis to absorb CO2 fix carbon and produce oxygen, seeding earths atmosphere. Decomposers such as mushrooms then evolved that took plant proteins and produce carbon dioxide and energy. The first oxygen users were the mollusks (insects, crustaceans, octopus) that had copper based blood that flowed through their body cavity. Octopus evolved a closed blood distribution that enabled oxygen to be delivered to key organs. Iron based blood (hemoglobin) in a closed circulation system then became universal in vertebrates from lampreys and fish onwards. Warm blood evolved in dinosaurs on, enabling much faster metabolism. The final evolutionary step increases the development of their young. Eggs provide a finite amount of energy to the developing fetus. Reptiles have fully developed, small, independent young when they break out of their eggs. Birds hide their underdeveloped young in nests while they feed them. Octopus' actively protect their eggs, sharks let them develop in their bodies for protection, and monotremes suckle their young after hatching. The placental mammals provide unlimited time and access to energy to maximize fetal development.
This evolution of species has progressed in bursts. The earth has changed over time; through continental drift, volcanism, orbit changes, meteor impacts etc. Each change affects climate, sea levels, and hence the vegetation, and all the life that feeds on the vegetation. A change that disrupts the local balance of between predators and prey, creates a new niche that provides an opportunity for new species to thrive.
There are 3 great explosion of species; the first populated the water around 500 Mya, the second populated the land around 300 Mya, the third re-populated the world after the K/T meteor 66 Mya that wipes out everything >50 lbs.
The most immediate source of competitive advantage when food is plentiful is size - the bigger wins ! Predation in forest favors large size because prey cannot run away, and large prey are difficult to bring down. However in open grasslands small size and agility becomes essential. Life in trees is another good way to avoid predators exploited by primates. Small size that can hide underground is another avoidance strategy. Diet driven adaptations also happen quickly, by natural variations and/or hybridization. Mutations are the engines of new capabilities such as placentals, whereas environmental changes that create new unfilled niches are the engines of species diversification. For example, mammals evolved underground as a minority while dinosaurs ruled. Underground mammals could not grow much larger or faster, but protecting offspring as they develop through much longer gestation and feeding after birth was a real competitive advantage. In addition, longer gestation and parental support encourages brain development. Then the K/T meteor cleared the dinosaurs out and mammals and birds exploded. Whereas, when all the niches are filled, such as either side of the Wallace line, new species have great difficulty migrating across the line and getting established.
The key functions that appear as the species evolve can be overlayed on the Mitochondrial tree proving a much more detail of the expansion of functionality.
It starts with a bacteria lipid walled, single cell with a ring of DNA. Cloroplasts evolved that could absorb sunlight. The first big branch is to plants with multiple cellulose walled cells with full DNA functionality in including Mitochondria. Mitochondria provide energy to the eukaryote cell by oxidizing sugars or fats and releasing energy as ATP. These two are responsible for the oxygen atmosphere. Mitochondrial DNA is inherited only from the mother and contains only information needed for the mitochondria to work.
Water living life started with a simple single and multicell structures such as bacteria, archaea or bacteria with genes, algae with photosynthesis, protozoa or scavenger cells, microscopic fungi that secrete digestive enzymes. Collectively known as "Plankton" they are food for small fish, bivalves and krill. The ancestors of land plants evolved in water. An algal scum formed on the land 1,200 million years ago. Molecular evidence suggests that the ability to generate electric signals first appeared in evolution some 700 to 800 million years ago.
Around 450 million years ago, the first land plants appeared. 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.
Next up are the Fungi, which 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. 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 Bilateria genetic thread led to 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.
Without a skeleton, octopus has very limited evolutionary options as a predator, but becoming a smarter prey is an 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.
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.
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 other became insect eating burrowers which led to todays mammals. It appears that by living in burrows, just like meercats, they survived predation by dinosaurs and extinction events for 200M years ! They slowly evolved into highly developed mammals that provided their growing offspring with unlimited energy through their placenta and milk. Mammals and birds thrived after the K/T meteor and share about 80% of their DNA, and a similar number of mutations from their common root over the same time span.
The first branch are called the sauropsids, led to dinosaurs and reptiles that are around today; Lizards, Snakes, Iguanas, 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, and the branch has no reptile survivors today but eventually evolved to mammals.
The skeletal evolutions were first synapsids followed by 3 middle ear bones (including marsupials) and then placentals. Synapsida[a] is one of the two major clades of vertebrate animals in the group Amniota, the other being the Sauropsida (which includes reptiles and birds). The synapsids were the dominant land animals in the late Paleozoic and early Mesozoic, but the only group that survived into the Cenozoic are mammals.[6] Unlike other amniotes, synapsids have a single temporal fenestra, an opening low in the skull roof behind each eye orbit, leaving a bony arch that provides anchor points for jaw muscles. The distinctive temporal fenestra developed about 318 million years ago during the Late Carboniferous period,[1] when synapsids and sauropsids diverged, but was subsequently merged with the orbit in early mammals. Originally, the openings in the skull left the inner cranium covered only by the jaw muscles, but in higher therapsids and mammals, the sphenoid bone has expanded to close the opening. This has left the lower margin of the opening as an arch extending from the lower edges of the braincase.
Based on the minuscule tubes of the inner ear, places the evolution of mammalian warm-bloodedness at around 233 million years ago .
https://www.livescience.com/warm-blooded-mammals-evolution
Warm bloodedness in dinosaurs is still a subject of debate. There is evidence for warmer blooded physiology, short of fully stable thermoregulation as in mammals. These include simple large size, high activity level generating heat. It seems most likely that dinosaurs had higher metabolism than reptiles, but not full thermo-regulation that was forced on small mammals with underground lifestyle.
https://en.wikipedia.org/wiki/Physiology_of_dinosaurs
Mass extinction events cause an explosion of new species. Numerous ecological niches are suddenly empty of both competition and predators. New herbivores and insectivores can flourish, eventually leading to new predators, and new balanced ecosystems.
At the end of Ordovician 430 M years ago was an extinction event that started the vertebrate fish era and coincides with the recovery from ice age extinction. The Late Devonian extinction event 370 M years ago started the amphibian era coincides with the recovery from an ice age. The Permo-Triassic extinction event 251 My ago radically changed the structures of communities with a 60% marine extinction. Ocean acidification decimated any species with calcium carbonate shells. This may have set the scene for the evolution of flowering plants in the Triassic (~200 million years ago), Conifers diversified from the Late Triassic onwards, and became a dominant part of floras in the Jurassic as a niche food source for huge herbivores. On land, there was the largest known mass extinction of insects. Aridification induced by global warming was the chief culprit behind terrestrial vertebrate extinctions. There is enough evidence to indicate that over two thirds of terrestrial labyrinthodont amphibians, sauropsid ("reptile") and therapsid ("proto-mammal") taxa became extinct. Large herbivores suffered the heaviest losses. Burrows containing early mammal fossils from just after the P-T extinction have been found in South Africa, presumably they were hiding from from the impact of the extinction.
Lystrosaurus a pig-sized herbivorous proto-mammal is notable for dominating southern Pangaea for millions of years during the Early Triassic. At least one unidentified species of this genus survived the end-Permian mass extinction and, in the absence of predators and herbivorous competitors, went on to thrive and re-radiate into a number of species becoming the most common group of terrestrial vertebrates during the Early Triassic; for a while, 95% of land vertebrates were Lystrosaurus. Of the survivors, only the 1.5 m (5 ft)–long therocephalian Moschorhinus and the large archosauriform Proterosuchus appear to be large enough to have preyed on the Triassic Lystrosaurus species, and this shortage of predators may have been responsible for a Lystrosaurus population boom in the Early Triassic.
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, did better than proto mammals that required parental support. 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 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.
Eutherians are distinguished from noneutherians by various phenotypic traits of the feet, ankles, jaws and teeth. All extant eutherians lack epipubic bones, which are present in all other living mammals (marsupials and monotremes). This allows for expansion of the abdomen during pregnancy,[1] though epipubic bones are present in many primitive eutherians.[2] The earliest unambiguous eutherians are known from the Early Cretaceous Yixian Formation of China, dating around 120 million years ago.
True placentals may have originated in the Late Cretaceous around 90 Mya. However, Elephants appear in Africa 60 Mya when Africa was an island between S America and Asia. The "Xenarthrans" (Sloths etc) in island S. America also date from 60 Mya. The fact that placentals appear in Africa, S. America and Laurasia (Europe + Asia) right after K/T suggest that rafts distributed them, similar to the migration of New World monkeys to S America around 25 Mya.
https://www.bristol.ac.uk/news/2016/february/rooting-the-family-tree-of-placental-mammals.html
The rafts may have been all the trees demolished in the K/T impact floating around. The different specialization in Africa snouted and S. America diggers may reflect the particular proto-mammals that hitched the ride on the rafts. For instance, Elephants Shrew are a close relative of Elephants. The fossil record suggests that the proto-mammals were centered in N. America, north of the impact point of the meteor.
The earliest undisputed fossils are from the early Paleocene, 66 mya, following the K/T extinction event. The species Protungulatum donnae is sometimes placed as a stem-ungulate [18] known 1 meter above the K/T boundary in the geological stratum that marks the K/T extinction event [19]. Ectoconus is another extinct genus of terrestrial herbivorous mammal of, endemic to North America during the Early Paleocene subepochs (66—63.3 mya) existing for approximately 2.7 million years.
Purgatorius, sometimes considered a stem-primate, appears no more than 300,000 years after the K/T boundary;[20] both species, however, are sometimes placed outside the crown placental group, but many newer studies place them back in eutherians.[21] The rapid appearance of placentals after the mass extinction at the end of the Cretaceous suggests that the group had already originated and undergone an initial diversification in the Late Cretaceous, as suggested by molecular clocks.[22]
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
After the KT impact, the small dinosaurs that were left evolved as warm blooded birds and cold blooded reptiles. Once the plant life recovered, all the resource niches occupied by large dinosaurs become available such as grasslands and tree tops accessed from land and air. The small dinosaurs that survived, evolved into the birds. The flightless birds such as ostrich were first. Overtime, flight allowed them to hide their young in nests. These young did not have to fend for themselves and were underdeveloped at the point when they used up all the food in the egg. The parents had to feed them until they could fly, supporting longer development time and greater functionality. The corvids (ravens, crows, jays, magpies, etc.) and psittacine (parrots, macaws, and cockatoos) are often considered the most intelligent. They demonstrate tools use. Cormorants have been shown to count to 7. Kea's also show malicious destruction including letting air out of tires. After the extinction, lobe finned fish disappeared and were replaced by ray finned fish. The "perch like" ray finned fish (Percomorpha) and the "perching" song birds (Passeriformes) thrived into tens of thousands of variants. Passeriformes feed on insects and in some cases nuts and fruits as well. Apparently they were particularly adapted to exploit the new environment after the KT impact. A 2017 study in the journal Science reported that a Galapagos finch immigrated to a new island and bred with a native bird, producing a new reproductively isolated lineage within three generations. That lineage may represent the very fast initiation of speciation via hybridization of species, rather than the slower accumulation of adaptations.
Dodos (relative of doves) unique to Mauritius located just off of Madagascar were made extinct by humans. Moa in New Zealand met a similar fate.
Phorusrhacids, colloquially known as terror birds, are an extinct family of large carnivorous flightless birds that were among the largest apex predators in South America from 53 to 0.1 million years (Ma) ago. Red-legged seriema in Southern S America are the closest survivors. Giant penguins appeared weighing 150Kg.
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:
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Primates - Monkeys, Apes, Humans
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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.
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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.
Fossils of Purgatorius, the oldest genus in a group of the earliest-known primates called plesiadapiforms are 65M years old. These ancient mammals were small-bodied and ate specialized diets of insects and fruits that varied by species. The first remains (P. unio and P. ceratops) were reported in 1965,[5] from what is now eastern Montana's Tullock Formation (early Paleocene, Puercan), specifically at Purgatory Hill (hence the animal's name) in deposits believed to be about 63 million years old, and at Harbicht Hill in the lower Paleocene section of the Hell Creek Formation. Both locations are in McCone County, Montana. They have also been found in the Ravenscrag Formation and widely discovered in the early Paleocene Bug Creek Group, along with leptictids.[6] These deposits were once thought to be late Cretaceous, but it is now clear that they are Paleocene channels with time-averaged fossil assemblages. It is thought to have been rat-sized (6 in (15 cm) long and 1.3 ounces (about 37 grams)) and a diurnal insectivore, which burrowed through small holes in the ground. In life, it would have resembled a squirrel or a tree shrew (most likely the latter, given that tree shrews are one of the closest living relatives of primates, and Purgatorius is considered to be the progenitor to primates). The youngest remains of Purgatorius date back to ~65.921 mya, or between 105 thousand to 139 thousand years after the K-Pg boundary.
Fossils like the proto-primate Plesiadapis is one of the oldest known primate-like mammal genera which existed about 58–55 million years ago in North America and Europe had some features of the teeth and skeleton in common with true primates. They were found in North America and Europe after 65Mya and went extinct by the end of the 33Mya. There was a Thulean Land bridge connecting Europe to N America until around 57 M years ago that could have been the path to populate Africa.
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
Monkeys originated in Africa and the first group known to have reached South America are thought to have migrated there on vegetation rafts up to 40 million years ago, when the land masses were probably between 1500 and 2000 kilometres apart, around a quarter of the distance now. Videos of pieces of land floating down the Panama Canal after a storm, show natural rafts that could have sustained upright trees that might have borne fruit. Monkey fossils in S. America date from 36M years ago.
In Columbia, "While travelling across a vast expanse of wetland, he passed an enormous floating island complete with tall trees and a resident colony of howler monkeys". As vegetarian fruit eaters, they could easily survive on an island with just trees for many months.
https://www.bbc.com/future/article/20210511-how-rafts-helped-primates-rule-the-world
Floating islands form during floods of the great tropical rivers when large masses of aquatic vegetation or chunks of their banks are torn away and carried downriver. The Congo in Africa is one such river, and floating islands that came down the Congo were reported 240 km out to sea from the river's mouth. Floating islands are also common in the Sepik river in Papua New Guinea following the monsoon rains. The islands are called "Lik Lik Aislans" in pidgin English, and can be up to 100 metres across with living trees on them. The Ro Paran and Ro de la Plata in South America also generate floating islands -- when they flood they are filled with floating islands called camalotes , which are matted masses of water hyacinth. A famous episode at Convento de San Francisco in Santa Fe, Argentina, which is located on the Ro Paran, involved the killing of two friars at the Convento by a jaguar that arrived on a camalote during a flood of the Paran on April 18, 1825. An example from Loktak lake, Manipur, India. In 2019 a pumice island 150 odd square kilometres in area was found in the Coral Sea.
https://www.downtoearth.org.in/coverage/floating-islands-of-the-world-8051
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.
Borneo is situated on the Asian side of the "Wallace Line", which is another example of the effect of geographic isolation on evolution. The Wallace Line that separates the biogeographical realms of Asia with elephants and tigers, and 'Wallacea', a transitional zone between Asia and Australia also called the Malay Archipelago and the Indo-Australian Archipelago with marsupials. The line runs through Indonesia, such as Makassar Strait between Borneo and Sulawesi (Celebes), and through the Lombok Strait between Bali and Lombok, where the distance is strikingly small, only about 35 kilometers (22 mi), but enough for a contrast in species present on each island. The complex biogeography of the Indo-Australian Archipelago is a result of its location at the merging point of four major tectonic plates and other semi-isolated microplates in combination with ancient sea levels.
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