Posts tagged fossil

weavercat: lostbeasts: biomedicalephemera: “Comparison of ancestral and existing horse” The lower figure is a model of a full-sized Eohippus, placed beneath the skull of a modern horse, to show that the skull of the modern horse is larger than the entire body of its ancestor. Despite being one of the most commonly cited “facts” in basic paleontology (as found in many elementary school science texts), this size comparison is actually incorrect. Geologist Henry Fairfield Osborn distributed (largely correct, aside from this point) educational pamphlets citing the size of Eohippus to be comparable to a “small fox terrier” to schoolhouses, to promote the science of paleontology, around the turn of the century. His pamphlets reached so far and wide that the “fact” still persists to this day in many textbooks. Eohippus was about twice the size of a fox terrier, which is about 2.5 times the size of a modern horse skull. Origin and History of the Horse. Address before the New York Farmers Metropolitan Club, 1905. i much prefer the name Eohippus to Hyracotherium Well, I prefer Hyracotherium as it is more closely related to paleotheres than ‘Eophippus’. Also, in college text-books, the freaking fox-terrier bit is still cited. Also, those feet look.. odd. Maybe it’s just me but they don’t look quite right. I thought the fifth toes on the forelegs were up ‘higher’ on the foot. The fifth toes weren’t higher up on the foot until Mesohippus, about 15 million years later. Hyracotherium was very wolf-like in its feet, though you can see from its leg structure that it had already begun the transition into a true prey animal, built for running long distances. Re: those college texts: It’s hard to criticize them currently, as a LARGE fox terrier can reach up to 15 inches, which would have been the size of a small “Eohippus”. However, when the pamphlet was written by Osborn, the standard size of a fox terrier was 13” tall - a small fox terrier would have been less than 8” at its withers, and was much smaller than the horse he purports it to represent.

weavercat:

lostbeasts:

biomedicalephemera:

“Comparison of ancestral and existing horse”

The lower figure is a model of a full-sized Eohippus, placed beneath the skull of a modern horse, to show that the skull of the modern horse is larger than the entire body of its ancestor.

Despite being one of the most commonly cited “facts” in basic paleontology (as found in many elementary school science texts), this size comparison is actually incorrect. Geologist Henry Fairfield Osborn distributed (largely correct, aside from this point) educational pamphlets citing the size of Eohippus to be comparable to a “small fox terrier” to schoolhouses, to promote the science of paleontology, around the turn of the century.

His pamphlets reached so far and wide that the “fact” still persists to this day in many textbooks. Eohippus was about twice the size of a fox terrier, which is about 2.5 times the size of a modern horse skull.

Origin and History of the Horse. Address before the New York Farmers Metropolitan Club, 1905.

i much prefer the name Eohippus to Hyracotherium

Well, I prefer Hyracotherium as it is more closely related to paleotheres than ‘Eophippus’. Also, in college text-books, the freaking fox-terrier bit is still cited. Also, those feet look.. odd. Maybe it’s just me but they don’t look quite right. I thought the fifth toes on the forelegs were up ‘higher’ on the foot.

The fifth toes weren’t higher up on the foot until Mesohippus, about 15 million years later. Hyracotherium was very wolf-like in its feet, though you can see from its leg structure that it had already begun the transition into a true prey animal, built for running long distances.

Re: those college texts: It’s hard to criticize them currently, as a LARGE fox terrier can reach up to 15 inches, which would have been the size of a small “Eohippus”. However, when the pamphlet was written by Osborn, the standard size of a fox terrier was 13” tall - a small fox terrier would have been less than 8” at its withers, and was much smaller than the horse he purports it to represent.

biomedicalephemera

“Comparison of ancestral and existing horse” The lower figure is a model of a full-sized Eohippus, placed beneath the skull of a modern horse, to show that the skull of the modern horse is larger than the entire body of its ancestor. Despite being one of the most commonly cited “facts” in basic paleontology (as found in many elementary school science texts), this size comparison is actually incorrect. Geologist Henry Fairfield Osborn distributed (largely correct, aside from this point) educational pamphlets citing the size of Eohippus to be comparable to a “small fox terrier” to schoolhouses, to promote the science of paleontology, around the turn of the century. His pamphlets reached so far and wide that the “fact” still persists to this day in many textbooks. Eohippus was about twice the size of a fox terrier, which is about 2.5 times the size of a modern horse skull. Origin and History of the Horse. Address before the New York Farmers Metropolitan Club, 1905.

“Comparison of ancestral and existing horse”

The lower figure is a model of a full-sized Eohippus, placed beneath the skull of a modern horse, to show that the skull of the modern horse is larger than the entire body of its ancestor.

Despite being one of the most commonly cited “facts” in basic paleontology (as found in many elementary school science texts), this size comparison is actually incorrect. Geologist Henry Fairfield Osborn distributed (largely correct, aside from this point) educational pamphlets citing the size of Eohippus to be comparable to a “small fox terrier” to schoolhouses, to promote the science of paleontology, around the turn of the century.

His pamphlets reached so far and wide that the “fact” still persists to this day in many textbooks. Eohippus was about twice the size of a fox terrier, which is about 2.5 times the size of a modern horse skull.

Origin and History of the Horse. Address before the New York Farmers Metropolitan Club, 1905.

biomedicalephemera: Latimeria chalumnae - Coelacanth The coelacanth was assumed extinct until 1938, since fossils of it had been found long before, yet hadn’t ever been caught by anyone who recognized it (it was known as the “gombessa” by the Comoro Islands fishermen, and was considered a worthless fish to be disgarded, as it tasted awful). It’s thought to have evolved over 400 million years ago, and were originally assumed to have gone extinct in the Late Cretaceous period. The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1956.

biomedicalephemera:

Latimeria chalumnae - Coelacanth

The coelacanth was assumed extinct until 1938, since fossils of it had been found long before, yet hadn’t ever been caught by anyone who recognized it (it was known as the “gombessa” by the Comoro Islands fishermen, and was considered a worthless fish to be disgarded, as it tasted awful). It’s thought to have evolved over 400 million years ago, and were originally assumed to have gone extinct in the Late Cretaceous period.

The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1956.

Underside and circulatory system of the Atlantic Horseshoe Crab (Limulus polyphemus)

The curious horseshoe crab (or king crab) is not actually a crab at all. It is an ancient member of the Chelicerata - more closely related to scorpions and spiders than any crustacean.

Note that the colors on the bottom illustrations only indicate a state of oxygenation and deoxygenation (red and blue, respectively), not the true color of the blood. Since horseshoe crabs utilize the copper-based hemocyanin to transport oxygen (as opposed to hemoglobin, in vertebrates), their blood is colorless or a light yellow when oxygenated, and a deep blue color when deoxygenated.

Of note - the mouth of the horseshoe crab is a jawless opening leading to a gizzard, between the legs on the underside of the body, and the book gills are located directly below them. The book gills, in addition to being used for blood gas exchange, are occasionally used for increased motility.

Images:

Top: Anatomy of underside and tail. From the John Reeves Collection, via scientificillustration. 1827.

Bottom: Circulatory system. Recherches sur l’Anatomie Limulus. M. Alphred Milne Edwards, 1873.

Platypodes being eaten by Teleosaurus and hunted by Pterodactylus Strictly speaking, platypodes did not exist in their current form back in the Late Jurassic (the only time Teleosaurus and Pterodactylus co-existed). When this illustration was published, Monotremata were thought to be “sub-mammalian”, and closely related to reptiles, and as such assumed to have split off from reptilian ancestors farther back than other mammalia. Thanks to genetic analysis, we now know that Monotremata are more closely-related to reptiles than other mammals, but not for the same reasons that were originally assumed. It’s unknown exactly when the order split from its last common ancestor to placental and marsupial mammals, but the oldest fossils we’ve found so far have only been 100 million years old or so. Those fossils were of Obdurodon, which looked a lot like a larger platypus with small shearing incisors, and molars in the back of its mouth. Aside from the fact that Teleosaurus was almost exclusively an open-ocean crocodilian, who knows? It might have snacked on an Obdurodon or two when it came to land to lay its eggs! The Book of the Animal Kingdom: Mammals. W. Percival Westall, 1910.

Platypodes being eaten by Teleosaurus and hunted by Pterodactylus

Strictly speaking, platypodes did not exist in their current form back in the Late Jurassic (the only time Teleosaurus and Pterodactylus co-existed). When this illustration was published, Monotremata were thought to be “sub-mammalian”, and closely related to reptiles, and as such assumed to have split off from reptilian ancestors farther back than other mammalia.

Thanks to genetic analysis, we now know that Monotremata are more closely-related to reptiles than other mammals, but not for the same reasons that were originally assumed. It’s unknown exactly when the order split from its last common ancestor to placental and marsupial mammals, but the oldest fossils we’ve found so far have only been 100 million years old or so. Those fossils were of Obdurodon, which looked a lot like a larger platypus with small shearing incisors, and molars in the back of its mouth.

Aside from the fact that Teleosaurus was almost exclusively an open-ocean crocodilian, who knows? It might have snacked on an Obdurodon or two when it came to land to lay its eggs!

The Book of the Animal Kingdom: Mammals. W. Percival Westall, 1910.

Top: Fossil Megaloceros giganteus with grown man for comparison.

Bottom: Approximation of Megaloceros giganteus in continental European environment.

The Irish Elk (Megaloceros giganteus), which wasn’t really an elk at all, wasn’t actually “Irish”, either. Though its fossils have been extensively preserved in the Irish peat bogs, and were first found in Ireland, this cervid lived throughout Eurasia, all the way east to Lake Baikal.

Their proposed extinction during the last major ice age has been disputed recently, with the dating of more recent bone caches. The current date that’s generally accepted for their (effective) extinction is around 7600 years ago.

Extinct Monsters. A Popular Account of Some of the Larger Forms of Ancient Animal Life. Rev. H. N. Hutchinson, 1896.

Essay on the Theory of the Earth. Baron Georges Cuvier, 1827.

scientificillustration: n352_w1150 by BioDivLibrary on Flickr. The Mammoth

scientificillustration:

n352_w1150 by BioDivLibrary on Flickr.

The Mammoth

Reconstruction of the Coelacanth from the fossil record The coelacanth is now known to have had fins that were a bit pointier than shown, but the general structure that was assumed here was very close to life. The lobe-finned fishes have two pectoral fins and two dorsal fins, all with separate bases, making them the first tetrapods (four-limbed creatures, which includes the land vertebrates). They also have teeth covered with true enamel, and are both cladistically and genetically more related to tetrapods than they are to the ray-finned fish. The Search Beneath the Sea: The Story of the Coelacanth. J. L. B. Smith, 1956.

Reconstruction of the Coelacanth from the fossil record

The coelacanth is now known to have had fins that were a bit pointier than shown, but the general structure that was assumed here was very close to life.

The lobe-finned fishes have two pectoral fins and two dorsal fins, all with separate bases, making them the first tetrapods (four-limbed creatures, which includes the land vertebrates). They also have teeth covered with true enamel, and are both cladistically and genetically more related to tetrapods than they are to the ray-finned fish.

The Search Beneath the Sea: The Story of the Coelacanth. J. L. B. Smith, 1956.

Thylacoleo (“marsupial lion”) skull fragments Richard Owen received and described these skull fragments in 1859. The extraordinary difference in one of the teeth presented to him led him to question the initial proposition that this was simply another extinct placental mammal. Comparing the mandibular structure and tooth structure to dasyures and thylacines versus the mandibular structure of the placental lion showed him that this was a marsupial mammal. On the Fossil Mammals of Australia Part I. Richard Owen, 1859.

Thylacoleo (“marsupial lion”) skull fragments

Richard Owen received and described these skull fragments in 1859. The extraordinary difference in one of the teeth presented to him led him to question the initial proposition that this was simply another extinct placental mammal. Comparing the mandibular structure and tooth structure to dasyures and thylacines versus the mandibular structure of the placental lion showed him that this was a marsupial mammal.

On the Fossil Mammals of Australia Part I. Richard Owen, 1859.

Latimeria chalumnae - Coelacanth The coelacanth was assumed extinct until 1938, since fossils of it had been found long before, yet hadn’t ever been caught by anyone who recognized it (it was known as the “gombessa” by the Comoro Islands fishermen, and was considered a worthless fish to be disgarded, as it tasted awful). It’s thought to have evolved over 400 million years ago, and were originally assumed to have gone extinct in the Late Cretaceous period. The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1956.

Latimeria chalumnae - Coelacanth

The coelacanth was assumed extinct until 1938, since fossils of it had been found long before, yet hadn’t ever been caught by anyone who recognized it (it was known as the “gombessa” by the Comoro Islands fishermen, and was considered a worthless fish to be disgarded, as it tasted awful). It’s thought to have evolved over 400 million years ago, and were originally assumed to have gone extinct in the Late Cretaceous period.

The Search Beneath the Sea: The Story of the Coelacanth. J.L.B. Smith, 1956.

Ammonite Fossils The Animal Kingdom, Arranged According to its Organization. Baron Cuvier, 1834.

Ammonite Fossils

The Animal Kingdom, Arranged According to its Organization. Baron Cuvier, 1834.

scientificillustration: n72_w1150 by BioDivLibrary on Flickr. A Belemnites puzosianus fossil. I’m always amazed when material as delicate as the soft tissue of a cephalopod is fossilised. Mollusques vivants et fossiles. Atlas.Paris :Gide et Cie., éditeurs,1845.biodiversitylibrary.org/item/50622 Ahhh, SI. Always finding what I don’t have. :3 I’m not so surprised when I see the beaks and cuttlebones preserved, but the tissues as soft as those of the squid and octopuses that have been found just blow the mind. They’re so much easier than plants to decompose, and it’s amazing that we’ve found even one that’s been preserved, let alone multiple individuals…

scientificillustration:

n72_w1150 by BioDivLibrary on Flickr.

A Belemnites puzosianus fossil.

I’m always amazed when material as delicate as the soft tissue of a cephalopod is fossilised.

Mollusques vivants et fossiles. Atlas.
Paris :Gide et Cie., éditeurs,1845.
biodiversitylibrary.org/item/50622

Ahhh, SI. Always finding what I don’t have. :3

I’m not so surprised when I see the beaks and cuttlebones preserved, but the tissues as soft as those of the squid and octopuses that have been found just blow the mind. They’re so much easier than plants to decompose, and it’s amazing that we’ve found even one that’s been preserved, let alone multiple individuals…

Ammonitida Can’t get much better than Hackel’s ammonites, in terms of illustration value. There are a few old interpretations of them as living creatures out there that look basically like the nautilus. Despite this, they’re more closely related to the extant coleoids - the squid, octopuses, and cuttlefish. Kunstformen der Natur. Ernst Haeckel, 1904.

Ammonitida

Can’t get much better than Hackel’s ammonites, in terms of illustration value. There are a few old interpretations of them as living creatures out there that look basically like the nautilus. Despite this, they’re more closely related to the extant coleoids - the squid, octopuses, and cuttlefish.

Kunstformen der Natur. Ernst Haeckel, 1904.

Skeleton of Mesohippus bairdi The Mesohippus lived in the late Eocene to early Ogliocene eras (30-40 million years ago), in North America. These proto-horses had three toes, and primarily used the center toe. Though they were structurally a long way off from the modern horse (not to mention only 60 cm/~2 ft tall), they were much closer to the Equus ferus we know than their ancestors, the Hyracotherium. Aside from their feet, their teeth and legs were moving quickly up the the evolutionary ladder. Notes on the Osteology of the White River Horses. Marcus S. Farr, 1896.

Skeleton of Mesohippus bairdi

The Mesohippus lived in the late Eocene to early Ogliocene eras (30-40 million years ago), in North America. These proto-horses had three toes, and primarily used the center toe. Though they were structurally a long way off from the modern horse (not to mention only 60 cm/~2 ft tall), they were much closer to the Equus ferus we know than their ancestors, the Hyracotherium. Aside from their feet, their teeth and legs were moving quickly up the the evolutionary ladder.

Notes on the Osteology of the White River Horses. Marcus S. Farr, 1896.

Fossil Reptiles and Fishes Fig 1 (the jaw and partial skull) is from the cretaceous-era reptile Mosasaurus hoffmani. The remainder of the figures (2-18) are “fossil teeth from various types of fishes, principally of the shark and ray families”. The plate-like “teeth” with parallel striations are from the rays. The pointy teeth are from the sharks. That big ol’ tooth in the center is from Carcharius megalodon - the shark known as “megalodon”. Literally translated from Greek, “megalodon” means “big tooth”. Fitting, eh? A Pictoral Atlas of Fossil Remains. Gideon Algernon Mandell, 1850.

Fossil Reptiles and Fishes

Fig 1 (the jaw and partial skull) is from the cretaceous-era reptile Mosasaurus hoffmani.

The remainder of the figures (2-18) are “fossil teeth from various types of fishes, principally of the shark and ray families”. The plate-like “teeth” with parallel striations are from the rays. The pointy teeth are from the sharks.

That big ol’ tooth in the center is from Carcharius megalodon - the shark known as “megalodon”. Literally translated from Greek, “megalodon” means “big tooth”. Fitting, eh?

A Pictoral Atlas of Fossil Remains. Gideon Algernon Mandell, 1850.