Earth Sci December Exam.docx

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Earth Sciences
Earth Sciences 1083F/G
William Marshall

Fossilization and Information Loss - Fossilization is rare - For dead remains to survive into fossil records requires exceptional conditions How Information in Fossils is Lost Scavenging - Low preservation potential of remains if exposed at the Earths surface (oxygen) - After an organism dies, its tissues are destroyed sue to a variety of factors - Large and small scavengers take their share of soft tissue Microbial Decay - Microbes break down dead organic matter further at the molecular level - Decay often proceeds from the inside out Physical (Mechanical) Weathering - Breaks down hard mineralized tissue (shells, bones, teeth) Chemical Weathering - Mineralized tissues tend to dissolve and erode at the surface Hard Parts are Preferentially Preserved - Hard parts have a greater chance of survival in the fossil record than soft tissues because hard parts are more robust, stable, and resistant to destruction - BUT are rarely preserved properly because soft tissue decay removes the connective tissue that holds the hard parts together Disarticulation  dissociation of hard parts Fragmentation  Breakage and dissociation of fragments thus formed Hard Parts that May Survive are Subject To - Dissolution  Breakdown of hard parts through the dissolution of minerals - Abrasion  Destruction of hard tissues due to “sandblasting” effects of suspended sediment particles Promote Preservation - Absence of oxygen slows down decomposition process and discourages scavenging - Rapid entombment (animal dies quickly) - Precipitation of stable minerals  calcium carbonate, calcite, silica, calcium phosphate Modes of Preservation Petrification/ Permineralization - Filling of pores with additional minerals - Iron carbonate - Gives us an idea how dinosaurs were reconstructed Silification - The original organic components of an organism are replaces by silica such as quartz, chalcedony or opal Pyritization - Marine environments (brachiopods) - Preserved with iron and sulfur Phosphatization - Hard parts filled with phosphate Molds and Casts - Internal mold  preserves the detail of the inner surface - Cast  Infilling of an external mold, all of the material that the outside material mold filled with other stuff - External mold  Preserves external features Soft Tissue Preservation - Muscles, skin … things that tend to rot away, therefore it is rare to preserve - Must be preserved immediately (buried alive) Carbonization - Formation of carbon from organic matter Refridgeration - May be preserved by ice Tar Impregnation - Taking a material that will preserve hard and soft parts - Something high in salt and vinegar = bacteria doesn't grow Phosphatization - Soft tissue replaced by phosphate Post Burial Process - Recrystallization  Overtime, crystals of a mineral tend to increase in size to achieve greater stabiityloss of detail - Compaction  When the sediment is soft, you can distort it Stromatolites: Trace fossils formation by sediment accretion Sediment trapping by bacterial silmemats and filaments will go through Coprolites: Fossilized poo The Origin of Life Domains Kingdoms 1. Archaea  Archaebacteria 2. Bacteria  Eubacteria 3. Eukarya  Protista, Plantae, Fungi, Animalia Nanobacteria - About 1000x smaller than regular bacteria - Debate lies in whether or not it is too small to contain genetic material Evolution of Earths Atmospheres 1. Initial atmosphere much like Jupiter (rich in Hydrogen and Helium from solar nebula) - Burned off by Solar wind/ escaped weak gravitational field - So far away from the sun they have attained their original atmosphere - As the sun began to undergo fusion and let off heat, losing the Jupiter like atmosphere 2. Second atmosphere much like Venus (dominated by carbon dioxide from Earth’s interior) - “The big bump” - Much like Earths second atmosphere, and rich in carbon dioxide from Earths interior through volcanoes - Extreme greenhouse 3. Third and present atmosphere (rich in oxygen) - Modified from second atmosphere due to rise of Anaerobic photosynthesizing organisms - Original atmosphere had no oxygen at all, but living things made earth have the oxygen rich atmosphere it has today Some Basic Characteristics of Living things - Metabolism  Living things harvest energy from environment, use energy to build, maintain their bodies - Regulation  Living things have a complex integrated system that controls conditions within their bodies - Replication  Living things can produce offspring - Response to external stimuli  Living things to respond to conditions of their external environment as individuals and larger populations Basic Stages Envisaged in the Development of Life Raw Ingredients - Assumed to have been present in the atmosphere and hydrosphere of early earth Monomers - Demonstrated to be capable of forming abiotically in Miller experiments - Used high energy electrons on a mixture of methane, water, and ammonia - Adenine, ribose, and deoxyribose synthesized abiotically - Problem: ingredients may not have been present in early life Polymers - Assumed to have formed through concentration, dehydration of monomers through… 1. Evaporation of solution near hot springs 2. Freezing and concentration of solution in cold environments 3. Adsorption into changed mineral surfaces Cell Membrane - Required to form the first isolated cell (containing complex material) - Lipids can form liposomes (hollow spheres of lipids) - Proteins will form microspheres when dehydrated and agitated Important Properties of Microspheres 1. Maintain separate stable phases in water 2. Membrane maintains electric pH and redox gradients Reproduction - Problematic: What came first? - Synthesis and replication of RNA happens with the help of enzymes - Proteins are synthesized using coded information in RNA and DNA Living Cell RNA World (The Naked Gene) - RNA can function as both 1. “information” molecules that can be replicated 2. Catalysts like protein enzymes as ribozymes Rationale of Naked Gene Hypothesis 1. Earliest life form was an energy harvesting RNA molecule that could catalyze it’s own replication 2. The RNA molecules most efficient at energy harvesting and producing themselves from environmental changes would win over less effective individuals 3. Natural selection would build complex metabolic and regulation systems incorporating protein enzymes 4. RNA that could replicate in double stranded form would proliferate since these forms would have two copies of each code, allowing better detection of errors in code Making Genetic Material Abiotically isn’t Impossible, but it’s Not Easy Problems 1. RNA, DNA are very complex molecules 2. Need high concentration of building blocks to concentrate and polymerize 3. Replication of RNA is a two step process - Single strand of RNA present, each of its links attract complimentary link (mirror image) out of prebiotic sources like making a zipper from one side as template for the other - Process would have to be repeated using new mirror image to duplicate original side (requires enzymes) Did Replication Start from Proteins? 1. Sheltered lagoon filled with tiny proteinoid microspheres 2. Proteinoids catalyze chemical reactions and form outer surfaces acting like cell membranes 3. Nucleic acids (DNA, RNA), formed on proteinoid enzyme templates 4. RNA or DNA evolve to function as replicator molcules 5. Splitting and fusion of microspheres with exchange of material The Clay Critter Revisited Properties of Mineral Crystals 1. The result of atoms naturally organized themselves 2. Organization at micro and macro scale 3. Clay minerals electrostatically charged, grow by adding layers to themselves (like pages in a book) 4. When broken, the fragments can continue to produce on their own (abiotic reproduction) Clay Critter 1. Growing clay crystals compete with each other for resources they grow 2. Crystals break apart, be transported in new area where they continue to grow and fragment again; in effect, the world is populated with competing clay beings 3. Genetic code in effect, charged mineral surfaces 4. Eventually clay critters begin to absorb and incorporate carbon based molecules to apparatus 5. Synthesis of DNA or RNA to augment and ultimately replace clay based genes Earths Earliest Life Origin of Life Recap How and where the first living cell came into beings… Possibilities: 1. That the essential ingredients for life were assembled in an aquatic environment (in dissolved form) and these were late incorporated into a cell membrane 2. That the cell membrane itself (a permeable membrane) acted to bring the ingredients together and that these were eventually incorporated inside the membrane 3. That the complex ingredients (including genetic material) were assembled on charged mineral particles, and were later encapsulated in a cell membrane (perhaps the membrane originating as an organic film that covered the mineral surface) Single Celled Prokaryote Microfossils – 3.5 billion years ago (Archean) Stromatolite 3.5 billion years (Archean) Filamentous Prokaryote Microfossils (Probably Cyanobacteria) 3.46 billion years ago (Archean) Key Points 1. Between 4.5 to 2.5 billion years ago, there was almost no OXYGEN present in either the hydrosphere or the atmosphere 2. From about 2.5 to 2.0 billion years ago, enough oxygen was dissolved in sweater to precipitate IRON oxides as sediment (forming magnetite and hematite in banded iron formations) 3. Beginning at about 2 billion years ago, there was enough oxygen in the atmosphere to oxidize (rust) iron on land – from here onward, banded iron formations decrease in abundance because iron was no longer dissolved in high quantities of seawater - Up to around 2 billion years ago, life flourished in the absence of OXYGEN Still, there are a few Interesting Points to Consider - The evolution of early, simple, life, (prokaryotes) was extremely SLOW (very little change over the span of 3.6 and 1.5 billion years ago) - Simple eukaryotes appeared by at least 1.5 billion years ago - Eukaryotes had a bit of a slow start (between 1.5 billion and at least 575 million years ago) then exploded in diversity upon the rise of multicellular forms Evolution of Sex and the Rise of Eukaryotes Two Main Types of Organisms 1. Prokaryotes (include Archaea and Bacteria) - Lack of nucleus 2. Eukaryotes (Eukarya only) - Has a true nucleus Prokaryotes - Very simple cells enclosed by cell wall containing an inner part of amino acids and sugars and an outer part of lipids - Have a single chromosome contained within a nucleoid region rather than a distinct membrane bound nucleus Reproduction - Simple process of binary fission 1. The cell makes an identical copy of its genetic material and each of the two copies ends up in each daughter cell 2. The daughter cells are clones of their parent - Advantage: reproduce quickly - Disadvantage: No genetic diversity and can be killed easily Eukaryotes - Complex cells with a membrane bound nucleus, and other structures such as mitochondria and plastids - Cells of eukaryotes are much larger than prokaryotes Production - In eukaryotes, genetic material is contained within the chromosomes, which are paired in the nucleus (humans have 23 pairs) - Have two ways can reproduce – Mitosis and Meiosis Mitosis - Involves the replication of genetic material and splitting to form clones - Function: The main process involved in maintaining tissue growth and to some extent reproduction Meiosis: - Involves splitting of the genetic material that can later be recombined (via sexual reproduction) to restore full genetic code - Function: Fundamental process involved in reproduction among eukaryotes (meeting of 2 cells, sperm and egg to produce an offspring Asexual vs. Sexual Reproduction Asexual  Prokaryotes - Mutation - Errors in code transcription Sexual  Eukaryotes - Mutation - Errors in code transcription - Crossing over and trading of genetic material between chromosomes pairs - Splitting and recombination of genetic material - Natural selection acts on these sources of variation to weed out the bad and keep the good. Sexual reproduction in eukaryotes ensures lots of variation and change Origin of Nucleus - Nucleus was produced by the infolding of the cell membrane and intaking the genetic material within the cell - Genetic material in chromosome like clump, and then the infolded membrane surrounds the genetic material But Not all Eukaryotes are Alike… Why do we have plants and animals? - Answer probably lies in the types of organelles eukaryotes possess Animals and Plants have mitochondria - The “power plants” of cells - Provide the energy a cell needs to move, divide, and produce secretory products - Food (sugar) is combined with oxygen to produce ATP (adenosine triphosphate) – the primary energy source for the cell - Similar to some bacteria in form and function Plants have plastids - The “food factories” of plant cells - It is here that photosynthesis occurs (energy from sunlight is harnessed to produce sugar) - Similar to cyanobacteria in form and function Endosymbiosis Theory - It has been suggested that mitochondria and plastids are actually bacteria that decided to reside in large host prokaryotes Could Eukaryotes have started out as big prokaryotes without mitochondria? - Giardia doesn’t have one, so it is likely that ancestral eukaryotes were able to survive without one as well - Thrives in an anaerobic environment and eats anaerobic bacteria. - Its ancestor probably had a mitochondrion, but Giardia evolved to live without one Serial Endosymbiosis Hypothesis 1. A prokaryote ingested some aerobic bacteria. The aerobes were protected and produced energy for the prokaryote 2. Over a long period of time, the aerobes become the mitochondria, no longer able to live on their own 3. Some primitive prokaryotes also ingested cyanobacteria, which contain photosynthesis pigments 4. The cyanobacteria become chloroplasts, no longer able to live on their own. - The basic thoughts on the origin of plant and animal cells 1. Aerobic bacterium becomes mitochondrion 2. Cyanobacterium becomes plastid Evidence for Origin of Mitochondria and Chloroplasts as “Guest” Bacteria - Mitochondria and chloroplasts are of similar size to bacteria - Have complex double membrane systems similar to bacteria - Fairly self contained, as if they derived from functional cells - Divide by binary fission (asexually) similar to bacteria Up to 575 million years ago, eukaryotes remained relatively simple in form (cysts, blobs, and strands) Then the snowball earth event happened Formation and Breakup of Rodinia - Supercontinent Rodinia forms at about 1100 million years ago - Rodinia breaks up at about 750 million years ago - Continents clustered near equator - Believed to have triggered the “snowball earth” The Snowball Earth - Almost entire earth froze over - Breakup of a single landmass (Rodinia) leaves small continents scattered near the equator - Carbon dioxide is removed from atmosphere by intense weathering of silicate rich continental rocks - Reduced carbon dioxide in atmosphere causes global temperatures to fail - Carbon dioxide more abundant than today 1. Before the Snowball - Ice packs form in the polar oceans, spread towards the equator - White ice reflects more solar enegery than darker seawater, driving temperatures lower - Starts a runaway glaciation effect 2. Into the Ice House - Temperatures to -50C - No rainfall, ice is 1 km thick - Most microscopic organisms die - No rainfall, so carbon dioxide emitted from volcanoes is not removed from the atmosphere 3. Snowball to Slush - 10 million years of volcanic activity raises carbon dioxide concentration - Greenhouse warming effect causes ice at equator to melt - Open waters in the tropics absorb more solar energy than ice, accelerating the warming of oceans 4. From Freeze to Fry - Over 50 C , intense cycle of evaporation and rainfall - Carbonic and acid rain weather and erode rock debris - Swollen rivers wash bicarbonate and other ions leading to deposition of carbonate sediment Survey of the Invertebrates - Latest Proterozoic (Ediacaran Period) - Oxygenated atmosphere and seas - Complex, soft bodied metazoa Adolph Seilacher - Concept of Vendozoa - Soft bodies - “quitted” structure (fluid filled bags) - Dependent on microbial mats - Fixed to seafloor, photosynthesizers” - Start out simple by a single celled protista - Phylum Protista: the importance of chanoflagellates - Some chanoflagellates form colonies that all individuals cooperate in moving their flagella, generating a current from which food particles can be extracted Sponges - Have collared cells, but these form a larger, integrated structure supported by rigid spicules or organic tissue - The differentiation of cells required by the evolution of HOX genes (genes that dictate differing functions of cells) - Sponges show a fractal organization - Two layers of tissue – ectoderm and endoderm Worms or Bilaterans - Most complex metazoan body plan - Trioblastic  3 principal cell layers: ectoderm, mesoderm, endoderm - Basic bilateral symmetry: fractal geometry breaks down, but tissue differention is incredible The Coelom - The ectoderm and endoderm can be viewed as essentially solid continuous layers - The mesoderm is a little more complicated in that it actually lines a fluid filled body cavity called the coelom - It is within the coelom that internal organs other than the gut develop Coelom and Orifice Development Protostomes - In the protostomes, the coelom develops directly from mesodermal tissue - Another distinguishing characteristic to the protostomes is the development of the mouth before the anus in the young embryo Deuterostomes - The coelom develops from out pockets of the gut - Another distinguishing characteristic to the protostomes is the development of the nus before the mouth in the young embryo Evolution of the Coelom - The coelom may have initially evolved as a hydraulic device - A bilateran with a coelom can squeeze its internal fluids with body muscles - The squeezing bulges the body wall at the weakest point can can be used as a power drill for burrowing - This pumping could facilitate the transport of oxygen through the body without relying on the bathing of tissues in oxygenated water by diffusion through a thin ectoderm - This means that animals could efficiently deliver oxygen through their bodies without compromising the effectiveness of their outer skins (ectoderm) or size - This also meant that animals could evolve exoskeletons Important Protostomes Flatworms - Do not have a coelom and it is likely that something like a flatworm gave rise to more advance coelomate bilaterans Phylum Mollusca, brachipoda, bryozoa, arthropoda Deuterstomes - Endchinodermata (spiny skin), Hemichordata, Chordata Evolution of Fishes - The origin of fishes can be traced to the first chordates (something like Pikaia or the modern Branchiostoma) that lacked a backbone but possessed a flexible rod of tissue called a notochord - Like other chordates, these have the basic worm-like body plan, muscle packs and a pharynx - Primitive Cephalochordates: Fish like forms without backbone (but with well differentiated head and body - Earliest fishes were jawless fishes, that evolved into jawed fishes - Diversity of fish peaked in the Devonian period. First True Fishes Jawless Fishes (Agnatha) Ancient Armoured (Ostracoderms) Evolution of Jaws (Step 1) - The evolution of jaws is an example of evolutionary modification of existing structures to perform new functions - Jaws are modified gill arches - Start with no jaws and many gill slits Step 2 - Lose first couple gill arches and modify third in line into solid jaws (upper mandible is upper part of arch becomes attached to skull, lower mandible remains free) Step 3 - Modify next gill arch in line into secondary components of the upper and lower mandibles First Jawed Fishes (Acanthhodians) - Distinguished by spines that supported primitive “fins” and slightly hardened internal skeleton - May have been ancestors of bony fishes - Range: Silurian Permian Placoderms - Distinguished by jaws and thick plates of bony armour - Fairly primitive jawed fishes - Hard outer skeleton Cartilaginous Fishes: Chondrichthyes - Sharks, rays, skates - Distinguished by cartilaginous skeleton, exposed gill slits, and skin with imbedded denticles - Silurian – Recent Bony Fishes - Fins supported by thin bones that radiate out from body - Fins attached to body by fleshy lobe with complex internal bone structure - Fins more robust and muscular than in any rayed rish - Devonian-Recent Rayfinned Fishes - Forms one usually thinks of as fishes - More diverse group of present day fishes Lobe finned Fishes - Once fairly diverse (palezoic) - Three major groups (Coelocanths, lungfishes, and rhipidistians) Evolution of Amphibians Middle to Late Devonian: Rhipidistians - Lungs were developed in two groups of lobe-finned fishes – Rhipdidstians and lungfishes - The rhipidistians are considered to be the ultimate ancestor of the tetrapods (vertebrate animals with four limbs adapted for life on land) - Rhipdipistian’s have evolved “land animal like features” approaching those of primitive tetrapods Tooth Structure - Labyrinthodont tooth structure is shared between Rhipidistian fishes and the earliest amphibians - Strongly supports the relationship between the two Skeletal Modifications - Skeletal structure of Rhipidistians was already similar to that of amphibians (especially in fins) Tirktaalik Fish Characteristics - Gills - Scales - Finns Amphibian Characteristics - Robust rib bones - Triangular skull shape - Neck with separate pectoral girdle (shoulder supports) - Functional “wrist” joint - Lungs – properly “Fishapod” Late Devonian - Ichthyostega was an early true tetrapod - Robust ribcage would have allowed greater lung breathing efficiency - Stronger pectoral and pelvic girdles allowed the primitive amphibians to cope with the minimal support provided by air on land - Special kind of skin that helped them retain bodily fluids and desiccation Change in Function of Limbs - Whereas fish ancestors used their tails for propulsion and their fins for maneuverability - Fishapods and tetrapods had begun to use their limbs for locomotion and their tail for balance Carboniferous to Permian - Amphibian nostrils became increasingly functional for breathing air - Amphibians evolved hands and feet with five digits - Amphibian tails became reduced in size - Amphibian backbones grew stronger (enabled their bodies to grow bigger) - Obtained eardrums Evolution of Neck and Ear - Fishes need limbs to support bodies and ears to hear sounds - Fins changed to legs - Several bones of the skull changed into shoulder bones - Tongue cartilage (part of the jaw in fish) became an earbone Amphibian Diversification - By the Permian period, amphibians had become quite diverse (some were very large) Advantages for Amphibians Living on Land - Less competition for food - Avoidance of large predatory fishes Disadvantages for Amphibians Living on Land - Amphibians have gas permeable skin to aid their inefficient lungs and it must be kept moist - Must have water to reproduce – water is needed for external fertilization - Amphibian jelly like eggs can not survive out of water Modern Amphibians 1. Anura  Frogs and toads 2. Caudata  Salamanders and newts 3. Apoda  Caecilians Evolution of Reptiles Amniote Egg - Great leap forward for tetrapods - Certainly not immune to various dangers posed by terrestrial conditions - Provides a great range of lifestyles that did the eggs of fishes and amphibians Outer Shell - An egg shell maintains space for embryo - The shell protects contents of the egg from outside conditions, but it is permeable to gasses Amnion - The amnion is a fluid filled sac in which the embryo floats - Amniotic fluid mimics the conditions that the embryo would require if the egg lacked a tough shell Outer Hull/Shell - The allantois serves two important functions 1. To deliver oxygen to the embryo and to take carbon dioxide away 2. To store excretory products Food Supply/Yolk - The yolk serves as the embyro’s principal food supply Water Supply/ Albumen - The albumen of the egg (the egg’s white) serves at the embryo’s water supply - Serves as an effective shock absorber Advantages of the Amniote Egg 1. Because amniote eggs were self contained units, they could be laid on dry land, away from water bodies 2. Embryos in amniote eggs were less prone to being adversely affected by changing environmental conditions (e.g. drying up of ponds, changing temperature, agitation due to storms and floods) 3. Greater strength of shells allowed animals to lay larger eggs which allowed a longer development period for the baby animal - Longer development time within the egg meant that babies were better equipped for survival after hatching Changes in Skin Texture - Another major modification made in the evolution of reptiles from amphibians was the development of a tough, dry, covering of keratin (the same protein in our hair and nails) on the surface of the skin - Scales and similar hardened structures on reptilian skin are made of keratin - The acquisition of a dry tough skin meant that reptiles were not in constant danger of “drying out” as are the amphibians Captorhinomorphs: Stem Reptiles - The oldest form of reptiles  Carboniferous period - This group of reptiles is believed to have been the stem for all later reptiles - Hylonomus, one of the oldest known captorhinomorphs has been found in Carboniferous rocks Skull Structure - The basis of amniote classification is the number and arrangement of holes behind the eye socket in the skull - With respect to these fenestrae, the most important bones are the POST ORBITAL and SQUAMOSAL bones Anapsid - The anapsid condition is characterized by the absence of temporal fenestrae - It is the most primitive skull type among the amniotes - The anapsid group includes the earliest “stem” reptiles (captorhinomorphs) and perhaps the turtles and tortoises Synapsid - Characterized by a single opening below the junction of the post orbital and squamosal bones - Includes the pelycosaurs (sail baked reptiles), mammal like reptiles (therapsids), true mammals Diapsids - Characterized by two openings – one above and one below the junction of the post orbital and squamosal bones - Represented by all of the archosaurs (ruling reptiles) - Snakes and lizards, thecodonts - Crocodilians, pterosaurs (flying reptiles) - Dinosaurs, birds Euryapsids - The euryapsid condition is characterized by single opening above the junction of the post orbital and squamosal bones - Represented by extinct marine reptiles: ichthyosaurs and plesiosaurs To Summarize Anapsids - No temporal fenestrae - Turtles, tortoises - Captorhinomorphs Synapsids - One temporal fenestrae low in skull - Pelycosaurs - Mammal like reptiles - Mammals Diapsids - Two temporal fenestrae’s - Lizards and snakes - Crocodilians - Pterosaurs - Dinosaurs - Birds Euryapsids - One temporal fenestra high in skull - Icthyosaurs - Plesiosaurs Limitations of Post Cranial Skeleton in “Primitive” Amniotes - One setback remaining for primitive reptiles was the sprawling stance imposed by the position of the legs relative to the body - A sprawling stance is fine for reptiles are active sporadically (ambush prey, or escape quickly but briefly) Limitations of Post Cranial Skeletons - The side to side motion that accompanies walking deforms the “chest cavity” with each bend and prevents lungs from expanding to their full capacity - The animal cannot sustain speed for long periods of time - Wastes a lot of energy waddling - A lot of stress is imposed on shoulder and hips (because most of the animal’s weight is supported at the junction between the limbs and the body Evolution of Dinosaurs Dinosaur Hip Structure Omithischian  All plant eaters, pubis is facing backwards, plant eaters need to eat more therefore they need larger stomachs Saurischian  Lizard hipped dinosaurs because the hips are similar to a lizard, ilium, pubis bone, ischium Saurischians Theropods - Killing machines from upright posture - Tail is essential for balance - Meat eaters Sauropods - All plant eaters - Work on all fours - Defense mechanism = tail Ornithischian Orhnitopods - Arose from sauropods - Hollow canal from the back of throat up into the nostril area - Function  mating sounds Stegosaurs - Plated dinosaurs - Peaceful plant eaters - Plates housed blood vessels  radiator that gains and subtracts heat - Digestion maintains heat Ceratopsian - Have a frill (shield) in the back - Function of the frill  skull is heavy so it gives the neck muscle attachment and allows the neck muscle attachment and allows the dinosaur to hold its head back Ankylosaurs - Back was covered in plates - Club of solid bone at the end of the tail - Had 4 toes on ground - Only way to kill it was on its back Pachycephalosaurs - Small bone headed dinosaur - Function of head  bash together to compete for mates Maiasaura: Good mother lizard Camouflage and keeps the eggs warm by burying them Oviraptor – “egg stealer” Bird Like Dinosaurs - Sinosauropteryx - Caudipteryx Marine Reptiles and Flying Reptiles - The greatest diversification of reptiles, beginning in the Triassic period and coming to a head in the Cretaceous period included the appearance and great success of marine and flying reptiles - Among the marine reptiles were the ichthyosaurs (euryapsids), plesiosaurs (euryapsids), marine turtles (anapsids or diapsids) and mosasaurs (diapsids) - In the Mesozoic area, pterosaurs ruled the skies Pterosaurs  Flying reptiles Ichtyosaurs  Marine turtles Mosasaurs  Great marine lizards Ichthyosaurs - Evolved from land dwelling reptiles with hands and feet - Modification of body for sea life  developed flippers Plesiosaurs - Evolved from a land dwelling reptile - Modification of limbs to form flippers, and lengthening of neck for darting movement to catch prey Marine Turtles - Large amount of biomass in the ocean - Turtles got very big Mosasaurs - Great marine lizards - Lizards that adapted aquatic life - Komodo dragon is the closest living thing - Evolved from land lizard, retaining lizard like body but limbs and tail modified for swimming - Common prey  other marine reptiles, birds, large ammonites (squid like molluscs) - They puncture the ammonites so they are no longer buoyant, then able to pull out the soft tissue Modifications for Flight - Extremely
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