We can only guess what the future will look like. But the past? We have evidence to help us paint a picture of it. To visit it.

There's a cool subreddit called 'Nature Was Metal' and its members are like online paleontologists, digging around the internet in search of pictures of dinosaurs and other creatures that are now extinct.

Often, they find pretty good ones: photos of real uncovered skeletons or image projections, built around them.

This subreddit is like a time machine, which may not physically take us to visit the long-gone days, but it certainly allows us glimpses of it, and that can be just enough to please our burning curiosity.

#1 “Dogor” An 18,000 Year-Old Puppy That Was Discovered In The Siberian Permafrost. He’s So Well Preserved That His Nose And Whiskers Are Still Mostly Intact

Image credits: TheEternels

#2 This Artist Tom Björklund Draws Neanderthals As People And Not As Biological Specimens. I Have To Say, Out Of All The Art I've Seen Of Neanderthals, This Is The One That Humanizes Them The Most

Image credits: Salt_x

Extinction has been a natural part of the planet's evolutionary history. In fact, 99% of the four billion species that have evolved on Earth are now gone.

And the process continues.

The International Union for Conservation of Nature (IUCN) Red List has tried to estimate the number of extinctions over the last five centuries but unfortunately, we don't know everything about all of the world's species over this period, so it's likely that some will have disappeared without us even knowing they existed in the first place, so its numbers can be an underestimate.

Still, that's the best guess we have. The IUCN Red List estimates that 900 species have gone extinct since 1500.

#3 Crinoid Fossils Can Be Found In Some UK Rivers And Were Once Thought To Be Fairy Coins. Sometimes Called ‘Star Stones’

Image credits: j3ffr33d0m

#4 Opalized Crab Claw

If a cavity has formed because a bone, shell or pinecone was buried in the sand or clay that later became rock, and conditions are right for opal formation, then the opal forms a fossil replica of the original object that was buried.

Image credits: KimCureAll

#5 It May Not Look Like Much, But This Tiny, Billion-Year-Old Green Algae Is The Ancestor Of All Land Plants On Earth

Image credits: Peachy-Persimmons

To understand the biodiversity problem we need to know how many species are under pressure; where they are; and what threats are they facing.

To do this, the IUCN Red List of Threatened Species evaluates species across the world for their level of extinction risk. It does this evaluation every year and continues to expand its coverage.

But the IUCN has not evaluated all of the world's known species. In many taxonomic groups, it has assessed only a very small percentage. In 2021, for example, it analyzed only 7% of described species.

#6 This Brachiosaurus Skeleton

Image credits: mtlgrems

#7 Indohyus - The Earliest Known Ancestor Of The Whale

Image credits: Animalnuttt

#8 Imagine Just How Huge And Metal This Mammoth Must Have Been... Tusk Of A Woolly Mammoth In Siberia

Image credits: mariospants

#9 Megalodon & Human Size Comparison

Image credits: _KingScar

As we'd expect, animals such as birds, mammals, and amphibians have seen a much larger share of their species assessed – more than 80%. On the other hand, only 1% of insects have. And less than 1% of the world's fungi.

The lack of complete coverage of the world’s species highlights two important points we need to remember when interpreting the IUCN Red List data:

1. Changes in the number of threatened species over time do not necessarily reflect increasing extinction risks;

2. The number of threatened species is an underestimate.

#10 This Isn’t A Dinosaur Fossil; It’s A Mummy

A 110 million-year-old Nodosaur was swept to sea by a flooding river, sank, landed on its back, and was pressed into the ocean floor. It’s so well- preserved that it still has intestines and weighs 2,500 of its original 3,000 lbs

Image credits: m0rris0n_hotel

#11 The Giant Monster That Was Argentinosaurus

Image credits: Husdjur

#12 A 120-145 Million Year Old Dinosaur With Two Heads Was Found In Yixian, China

It's super rare because the chances of a two headed animal are small and for it to even fossilize are even smaller.

Image credits: Narendra_17

#13 In 1982, The Comic Strip 'The Far Side' Jokingly Referred To The Set Of Spikes On A Stegosaurus's Tail As A "Thagomizer". A Paleontologist Who Read The Comic Realized There Wasn't Any Official Name For The Spikes And Began Using The New Word; "Thagomizer" Is Now The Generally Accepted Term

Image credits: mtlgrems

In total, the IUCN Red List has evaluated 40,084 species across all taxonomic groups to be threatened with extinction in 2021.

But as noted before, since birds, mammals, and amphibians are the most well-studied groups, their numbers are the most accurate reflection of the true number (and therefore, understudied groups such as insects, plants, and fungi will be a large underestimate).

#14 Outdated Reconstruction Of A Neanderthal vs. Scientifically Accurate Reconstruction Of A Neanderthal

Image credits: AddisonDeWitt_

#15 A Raptor And Protoceratops’ Fight Preserved In The Sand

Image credits: Peachy-Persimmons

#16 The Last Photo Taken Of A Wild Barbary Lion. Taken In 1924

Image credits: 2005Cule

#17 A Neanderthal Father With His Child. Reconstruction Made By The Kennis Brothers

Image credits: AddisonDeWitt_

Many think that humans are also doomed to disappear. Paleontologist Henry Gee thinks the most insidious threat to humankind is the so-called extinction debt.

"There comes a time in the progress of any species, even ones that seem to be thriving, when extinction will be inevitable, no matter what they might do to avert it," Gee wrote in Scientific American.

"The cause of extinction is usually a delayed reaction to habitat loss. The species most at risk are those that dominate particular habitat patches at the expense of others, who tend to migrate elsewhere, and are therefore spread more thinly. Humans occupy more or less the whole planet, and with our sequestration of a large wedge of the productivity of this planetwide habitat patch, we are dominant within it. H. sapiens might therefore already be a dead species walking."

#18 The Diversity Among Homo Erectus Around The World. Homo Erectus Existed For 1.9 Million Years And Was The Most Successful Human Species

Image credits: AddisonDeWitt_

#19 A Comparison Between The Skull Of A Sarcosuchus And A Nile Crocodile

Image credits: No-Promotion-2955

#20 Sue Is The Largest T.Rex To Be Found So Far, At 90% Of The Body Complete

Image credits: Peachy-Persimmons

#21 Reconstruction Of Sue, The T. Rex, In The Field Museum In Chicago

Notice the eyes and the snout, to this day I never saw a reconstruction that looked terrifying and cute at the same time. Blue Rhino Studio made the model for this exhibition. Photo taken from their Facebook page.

Image credits: AlJRaba

"The signs are already there for those willing to see them," Gee said. "When the habitat becomes degraded such that there are fewer resources to go around; when fertility starts to decline; when the birth rate sinks below the death rate; and when genetic resources are limited—the only way is down. The question is 'How fast?'"

The paleontologist suspects that the human population is set not just for shrinkage but collapse. I guess, time will show.

#22 Around 26000 Years Ago This Lion Cub Was Abandoned In A Siberian Cave By Her Mother Who Either Went Hunting, Or Was Killed Never To Return

Unable to feed herself, the cub dubbed Sparta starved and has been perfectly preserved since.

Image credits: xindigothoughtsx

#23 Triceratops Femur (Left) vs. Elephant Femur

Image credits: TheGreatHsuster

#24 23 Million Year Old Lizard Found In Fossil

Image credits: Peachy-Persimmons

#25 A Rare Fossil: The Shell Of A Tortoise Stuck In The Jaw Of An Ancient Elephant

Image credits: Scientiaetnatura065

#26 10 Million Years Ago, Turtles Could Eat You With A Single Bite

Image credits: billenbijter

#27 100,000 Years Ago, A Group Of Neanderthals In Spain Walked Down To The Beach

Image credits: sylvyrfyre

#28 The Licking Bison Of La Madeleine Was Carved On A Reindeer Antler Fragment In Upper Paleolithic France Sometime Between 20,000 And 12,000 Years Ago. It Depicts The Now Extinct Steppe Bison

Image credits: Pardusco

#29 These 250-Million Year Old Detailed Crinoid Fossils

Image credits: Peachy-Persimmons

#30 Quetzalcoatlus, The Biggest Flying Animal Ever!

Image credits: Rabano11

#31 Livyatan Is An Extinct Genus Of Sperm Whale And Is Most Notable For Being A Member Of The Raptorial Sperm Whales (Hyper-Predatory Sperm Whales) And Having The Strongest Bite Of Any Tetrapod

Image credits: tgood139

#32 When Breeding, Australian Gastric-Brooding Frogs (Rheobatrachus) Would Stop Producing Gastric Acid, Swallow Their Eggs, And Carry Them In Their Stomachs Past Metamorphosis. Extinct Since 1985

Image credits: masiakasaurus

#33 Tail Of A 99m Yo Dinosaur, The First One Ever Discovered. Perfectly Preserved, Still Covered In Feathers

Image credits: Tangledtitty

#34 An Incredibly Intact Crinoid Specimen Fossil Dating Back To About 345 Million Years Ago!

Image credits: monomotive

#35 Cretan Dwarf Mammoth. It's Possible Its Skull Was The Origin Of The Myths About Cyclops In Ancient Times. (Not My Photo)

Image credits: ACJ96

#36 This Was Toughie, The Last Known Living Rabbs' Fringe-Limbed Treefrog. He Was Captured As An Adult In Panama In 2005 And Died In Captivity On September 26, 2016

Image credits: Pardusco

#37 Prehistoric 'Hell Ant' Stuck In Amber Biting It's Prey For 99 Million Years

Image credits: Jeski221

#38 A Megalodon Tooth Compared To A Great White Shark!

Image credits: Rayan2550

#39 A Preserved Foot Of The Giant Moa Bird. An Extinct Species Native To New Zealand. It Grew To Be 12 Feet Tall

Image credits: Sleeeepy_Hollow

#40 I See Your Various Well-Preserved Animals And Raise To You A Smushed Baby Mammoth (Credit Ruth Hartnup)

Image credits: reddit.com

#41 Skeleton Of Archelon Ischyros

Image credits: Ryunysus

#42 An Argentinian Farmer Recently Found 20,000 Years Old Fossilized Glyptodons

Image credits: Peachy-Persimmons

#43 This Spinosaurus Skeleton

Image credits: mtlgrems

#44 57,000 Year-Old Wolf Puppy Found Frozen In Yukon Permafrost | Photograph By Government Of Yukon

Image credits: reddit.com

#45 Titanoboa Skeleton

Image credits: Ryunysus

#46 This Rare 30,000 Year Rare Blue Mammoth Tusk Discovered In Alaska In 2017

Image credits: hconfiance

#47 Giant Chinese Paddlefish Now Officially Extinct

Image credits: iam1whoknocks

#48 The Mosasaurus In Jurassic Park Compared With An Actual One

Image credits: No-Promotion-2955

#49 This Woolly Rhino Specimen Fell Into An Oil Well And Was Perfectly Preserved For Tens Of Thousands Of Years. [museum Of National History, Lviv]

Image credits: Jeemdee

#50 Prehistoric Spider-Like Arachnid Found Preserved In Amber

Image credits: Tangledtitty

#51 The World’s Only Intact Fossil Of An Early Whale - The Basilosaurus Dating About 40 Million Years Ago - Has Been Uncovered During A Excavation At Wadi Al-Hitan In Egypt

Image credits: jaketocake

#52 Sub-Adult Torosaurus Skull Compared To A Fully Grown Man

Image credits: hadrosaur-harley

#53 The 10,000 Year Old Skull Of An Extinct Giant Irish Elk Found By A Fisherman

Image credits: TheEternels

#54 The Kronosaurus Skeleton At The Harvard Museum Of Natural History

Image credits: tgood139

#55 Had To Drive 14 Hours To Get Her, But I Finally Have My Little Own Coelophysis

Image credits: thebriss22

#56 These Starfishes Embedded In Stone As A Fossil

Image credits: Peachy-Persimmons

#57 The Size Of A Syrian Camel, The Largest Fossil Camel Known With Weights Of Up To 3 Tons

Image credits: aquilasr

#58 4,000-Year-Old Thylacine Mummy Found In Cave In Western Australia

Image credits: Risingmagpie

#59 A Prime Specimen Of T. Rex Skin Suggests That The King Of Dinosaurs Was Covered In Scales, Not Feathers

Image credits: Peachy-Persimmons

#60 The Caspian Tiger, Extinct For Nearly 50 Years. These 300+ Pound Cats Once Ranged Throughout Turkey, Iran, Iraq, Northwestern China, And Much Of Central Asia. This Pic Is From 1871

Image credits: hamoxi4354

#61 An Amazingly Well Preserved Trilobite From The Devonian Age

Image credits: Peachy-Persimmons

#62 Siberian Permafrost Reveals Perfectly Preserved Ice-Age Baby Horse That Died Between 30,000 And 40,000 Years Ago

Image credits: imhalfmermaid

#63 California Grizzly Bear, The Bear On The California Flag Which Was Extinct In 1924 Due To Overhunting

Image credits: edgarzekke

#64 Scientists Investigating A Dried-Up Lava Tube In Northwestern Saudi Arabia

Were stunned to find a huge assemblage of bones belonging to horses, asses, and even humans (over 40 species total, possibly some now extinct) that were dragged to this location by striped hyenas about 7000 years ago.

Image credits: KimCureAll

#65 Model Of A Diplocaulus

Image credits: Krivus20

#66 A Squidlike Creature That Looked Like A Giant Paper Clip Lived 68 Million Years Ago In The Southern Ocean Around Antarctica. It May Have Lived As Long As 200 Years

Image credits: sylvyrfyre

#67 A Meeting Between A Neanderthal And A Homo Sapiens. This Reconstruction Is Displayed In The Natural History Museum In London And Was Made By The Kennis Brothers

Image credits: AddisonDeWitt_

#68 Gigantopithecus Blacki Is A Species Of Great Ape, Who's Closest Living Relative Is The Orangutan. It Stood At Approximately 3 Metres Tall, And Is Thought To Have Lived As Recently As 100,000 Years Ago. Meaning It Co Existed With Early Humans!

Image credits: Cyclonimus

#69 11,000 Years Ago These Giant Armadillos Called "Glyptodonts" Existed Among Humans, And They Probably Went Extinct Because They Were An Easy Food Source For The Humans

Image credits: ilikedoodless

#70 The Size Of Sue, The T.rex

Image credits: MoRbidanGeL23

#71 Giant Fossil Of A Kronosaurus

Image credits: Radiaids

#72 Behold, The Armored Fish From The Devonian Period: The Dunkleosteus!

Image credits: SCP_fan12

#73 Great News: Up To 60-100 Mammoths Have Been Found In Southern Mexico

Image credits: fwzain

#74 The Only Preserved Head And Skin Of The Extinct Dodo Bird, Kept At The Oxford University Museum Of Natural History

Image credits: fwzain

#75 Utahraptor Claws

Image credits: TheGreatHsuster

#76 A 50-Million-Year-Old Fossil Captures A Swimming School Of Fish

Image credits: earthymalt

#77 An Trionyx Fossil. Note The Bones Jutting Out From Its Sides

Image credits: Peachy-Persimmons

#78 The Skull Of A Triceratops Compared To That Of A Centrosaurus

Image credits: levi2207

#79 Researchers In Madagascar Discovered The Remains Of An Extinct Species Of Horned Crocodile In A Water-Filled Cave

Image credits: KimCureAll

#80 Millions Of Years Old Whale Skeleton In Wadi El Hitan In Egypt From The Time When The Area Was A Sea

Image credits: hanfinho123

#81 This Is The Steppe Bison Blue Babe. 36,000 Years Ago He Was Attacked And Escaped From An American Lion Attack, But Later Died To Injuries. Alaskan Permafrost Kept His Hair, Skin, Tongue And Other Organs Fresh Until His Discovery In 1979

Image credits: Froskr

#82 Spinosaurus

Image credits: Anubisgod123

#83 Libyan Rock Art Depicting Syncerus Antiquus With A Cattle Egret Perched On Its Horn

Image credits: Pardusco

#84 The Preserved Carcass Of A Woolly Rhinoceros Found Frozen In Siberia

Image credits: Pardusco

#85 The Evolution Of Our Face

Image credits: Ivan_Botsky_Trollov

#86 Fossils Of 2 180 Million Year Old Dinosaurs Discovered Unearthed Beneath Road In China!

Image credits: Rayan2550

#87 Stan The Tyrannosaurus Rex Sold At An Auction For $31.8 Million!

Image credits: Rayan2550

#88 The Barosaurus And Allosaurus Encounter At The American Museum Of Natural History

Image credits: nicobarca

#89 The Skull Of "Bloody Mary", One Of The 2 Dinosaus Found Locked In Combat In The "Dueling Dinosaurs" Specimen

Image credits: HourDark

#90 Theropod/ Dilophosaurus Footprint In Utah

Image credits: JWrither

#91 57,000 Year Old Wolf Pup Mummy Uncovered In Yukon Permafrost. She Is Almost 100% Intact And Only Her Eyes Are Missing

Image credits: Pardusco

#92 A Cave Bear Mummy Found In Russia

Image credits: levi2207

#93 A Shark Tooth Embedded In A Pterosaur Vertebra

Image credits: Oplytr

#94 A Bear Body Made From Clay With A Bear Skull In Between Its Paws, Made By Prehistoric Humans. Riddled With Holes From Spear Points, It Was Possibly Used To Teach Hunting, Or Served A Ceremonial Purpose

Image credits: rsunds

#95 Columbian Mammoth Remains Excavated In Mexico. This Species Of Mammoth Has Been Found As Far South As Nicaragua And Honduras

Image credits: Pardusco

#96 3000 Pound Triceratops Skull Unearthed In South Dakota

Image credits: sylvyrfyre

#97 Deinosuchus Skull Compared To An Alligator Skull

Image credits: hadrosaur-harley