¿Por qué los DINOSAURIOS eran TAN GRANDES?

Introduction to Micoplasma and Animal Sizes

The Smallest Living Organism

• Micoplasma is introduced as the smallest living organism, measuring 0.2 micrometers in length, significantly smaller than a human hair which measures 130 micrometers.

The Largest Animals in History

• Discussion shifts to the largest animals, defining "animal" from its Latin roots meaning soul or life. There are various species categories including arthropods and chordates.

Arthropods vs Chordates

Size Comparison of Arthropods

• Current largest arthropods like the Archispirostreptus gigas measure only a few centimeters; historically, the Arthropleura was the largest terrestrial arthropod at over 2 meters long.

Transition to Chordates

• Focus moves to chordates, specifically vertebrates, which include some of the largest land animals today such as giraffes and elephants.

Ranking of Large Animals

Top Three Largest Land Animals

• 3rd Place: Giraffe - tallest at 5.7m and weighing one ton.

• 2nd Place: White Rhinoceros - up to 4m long and weighing around 2.3 tons.

• 1st Place: African Savannah Elephant - endangered species standing at about 3m tall and weighing over 6 tons.

Historical Giants

Ancient Mammals

• Mention of ancient mammals like mammoths (up to 4m tall, weighing 14 tons) and Paraceratherium (4.8m tall, weighing up to 17 tons), highlighting their massive sizes compared to modern animals.

Dinosaurs: The Giants of Prehistory

Perception of Dinosaur Size

• Common belief is that dinosaurs were enormous; however, not all were large—example given is a hummingbird-sized dinosaur measuring approximately 6 cm and weighing just 2 grams.

Birds as Modern Dinosaurs

• All birds are scientifically classified as dinosaurs due to their lineage from theropods like Tyrannosaurus Rex; current largest dinosaur is considered the ostrich today.

Misconceptions About Dinosaurs

Appearance in Media vs Reality

• Clarification on Velociraptors having feathers based on paleontological discoveries contradicting their portrayal in films like Jurassic Park where they are depicted with crocodilian skin and larger size than reality suggests (about chicken height).

The Largest Dinosaurs

Sauropods Overview

• Discussion on sauropods such as Diplodocus, Brachiosaurus, leading up to Argentinosaurus being noted as the heaviest dinosaur ever recorded at approximately 35 meters long and weighing around 80 tons.

Why Were Dinosaurs So Large?

Theories Behind Size Evolution

• One theory posits that Earth's gravity was lower in prehistoric times allowing for larger sizes; Newton's principles regarding gravity's dependence on mass are referenced but ultimately dismissed for this explanation due to insufficient evidence regarding mass changes over time from meteor impacts or gas loss from Earth’s atmosphere.

Physical Limitations on Size

Scaling Laws Explained

• Introduces the square-cube law explaining how increasing size affects volume disproportionately compared to surface area; implications for bone strength discussed—larger bones must support more weight but also become heavier themselves leading towards physical limits on growth potential for large animals like dinosaurs versus smaller creatures like hamsters or ants which can withstand different weight ratios effectively due to structural differences in their bodies .

Unique Adaptations of Dinosaurs

Hollow Bones Advantage

• It’s explained that sauropods had hollow bones similar to modern birds which allowed them greater size without proportionate increases in weight—this adaptation facilitated their ability grow much larger than mammals could manage under similar conditions .

Reproductive Strategies

Egg-Laying Benefits

-Dinosaurs’ reproductive strategy involved laying eggs rather than gestating young internally allowing them freedom from weight constraints during development enabling larger body sizes compared with mammals whose gestation periods increase with size .

Evolutionary Pressures Leading To Giant Sizes

Survival Of The Fittest Concept

-The evolutionary arms race between theropod predators hunting down herbivorous sauropods led those surviving into becoming increasingly larger over millions years creating an environment favoring giant forms among these species .

Conclusion: Present-Day Comparisons

Current Largest Animal

-Mentioned that while many ancient giants existed , today’s blue whale holds title for largest animal ever known , emphasizing unique moment we live witnessing such immense creature still alive today .