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Description
Diplodocus hallorum

Diplodocids are some of the most iconic dinosaurs of the Jurassic. With a myriad of species dominating the Morrison Formation in the Rockies and Great Plains of the United States. Among the largest of all Diplodocids from that region is Diplodocus hallorum or Seismosaurus.

Discovery:

It was originally discovered in 1979. Local hikers Arthur Loy, Jan Cummings, Frank Walker and Bill Norlander came across bones sticking out of the ground parallel to a hiking trail. They reported their discovery to the Bureau of Land Management. It was not excavated immediately due to their lack of resources at the time. In 1985, paleontologist David Gillette had finally been contracted to unearth the specimen. The holotype specimen consisted of vertebra, pelvis, and ribs. After 6 years of it residing in the New Mexico Museum of Natural History Gillette gave a name to the fossils. He called it "Seismosaurus halli", the species name honors Jim and Ruth Hall, a husband and wife team who ran the Ghost Ranch Museum and were good friends of Gillette. And Seismosaurus, the genus name literally means "Earthquake Lizard". However, since it was named after two people, Gillette's colleague George Olshevsky suggested making it "Seismosaurus hallorum". Gillette agreed and that was the name that was settled on for the next 15 years.
However, subsequent studies from 2006 and 2015 have regarded this animal as being a separate species of Diplodocus. The studies determined that there is no distinguishing anatomical difference between the Seismosaurus and Diplodocus aside from their size. Furthermore, the study in 2015 led by Emanuel Tschopp et.al found that most of the material belonging to the type species of Diplodocus, "Diplodocus longus" actually belongs to Diplodocus hallorum (other material that was assigned to D.longus is dubious or belongs to other Morrison sauropods). Thus, the animal has been reclassified as Diplodocus hallorum or Hall's Double-Beam.

Fossils:

Fossils attributed to this dinosaur have been found in Utah, Wyoming, and New Mexico. It would have shared the environment with Jurassic icons like Brontosaurus, Stegosaurus, and Camarasaurus. It also lived with a variety of predators like Allosaurus, Torvosaurus, and Ceratosaurus. These predators would have been more than capable of preying upon juvenile sauropods.

Size:

When it was first excavated, Diplodocus hallorum was thought to be one of the largest land animals that ever lived. Estimates ranged up to 180ft long and weighing as much as 100 tons.
However, it's now known that the size of these giants is vastly over-estimated. With bones filled with air-sacs, this animal likely was far lighter than previously thought. Perhaps ranging from 25 to 35 tons. Its size was based on more outdated methods of calculating size in dinosaurs. However, it was still a massive and awe-inspiring giant, roaming the fern prairies and scrubland of the Morrison Formation. With some individuals reaching lengths of over 100ft.

Habitat:

The environment of the Morrison Formation was a floodplain environment with lowland swamps and vast fern prairies with cycad and horsetail being the primary flora in the region. Conifers such as redwoods and monkey-puzzle trees are among the predominant conifer trees in the area. The trees and ferns would have been the primary browsing material for sauropods like Diplodocus and its kin. As far as how long these animals lived, they were only around for 2,000,000 years from 154-152,000,000 years ago, based on the rocks where the fossils were collected.

Rearing Behavior:

A trend commonly seen in Paleoart is sauropods rearing up on their hind legs to feed on taller trees. While definitely an awe-inspiring sight to behold in paleoart, was this actually possible for them to achieve? Recent studies have found support for this theory in most diplodocids across the board. For one, for a third of the way down the tail, bottom chevrons are strangely boat-shaped, perhaps used to provide support for the animal as it used its tail as a prop. Furthermore, the center of mass was placed near the hind limbs, an ideal position for the animal to rear up. So it's possible that these diplodocids could have reared up.

Diet:

Like all Sauropods in the Late Jurassic, Diplodocus hallorum was a herbivore. Its skull was equipped with peg-like teeth and they were believed to be used to strip plant material from horsetail, conifers, or ferns. Many paleontologists have theorized that diplodocids used unilateral branch stripping to feed. One row of teeth would grab the stem of the foliage, and the other would guide the stripping of the plants. They would then swallow down the plant matter and have it digest in their massive gut, no pre-processing of the food (chewing) would occur in the mouth. All processing of its food would occur in its massive gut.

Diplodocus hallorum is one of the largest sauropods that lived in the Morrison Formation. It remains an icon of the Jurassic, and one cannot deny the power and size of this magnificent creature.
___________________________________________________________________________________________

6/22: I updated it with a modified Barosaurus model and decided to bring it more in line for its appearance in the next episode of Past Meets Present as well as updated its statistics.

The main updates I made to the model were:
-A more fleshed out neck and head, where the flesh actually meshes from the neck into the head a lot better and doesn't have that shrink-wrapped look to it.
-Nostrils moved up to the front of the head.
-A resonation chamber.
-A more upright neck posture.
-Having spikes go all the way down to the tail.
-Finally, I added in claws onto its hands and feet. This is an aspect I have rarely seen done properly for Sauropods. The hands and feet are not just carbon copies of elephant limbs. The hand is hollow with most species having an enlarged claw outside forming a shape almost like a hoof. Whereas, the feet have 3 claws curving slightly to the side. This is something found on virtually every sauropod.

Furthermore, as much as I like the color scheme of the iconic WWD Diplodocus, I honestly cannot see a Sauropod having a bland, boring color scheme on its body. So I did a bit of modification to the skin, giving it a distinctive nose coloring and giving it stripes.

For more details on Sauropods, Darren Naish did an EXCELLENT blog post on the subject:
The Life Appearance of Sauropod Dinosaurs — Tetrapod Zoology (tetzoo.com)

For Past Meets Present:
Past Meets Present (Pt4 is Up) - Page 2 - The ZT2 Round Table

Original model by DinosaurManZT2 modified by me:
Diplodocus (HENDRIX) | ZT2 Download Library Wiki | Fandom

Description
Diplodocus hallorum

Diplodocids are some of the most iconic dinosaurs of the Jurassic. With a myriad of species dominating the Morrison Formation in the Rockies and Great Plains of the United States. Among the largest of all Diplodocids from that region is Diplodocus hallorum or Seismosaurus.

Discovery:

It was originally discovered in 1979. Local hikers Arthur Loy, Jan Cummings, Frank Walker and Bill Norlander came across bones sticking out of the ground parallel to a hiking trail. They reported their discovery to the Bureau of Land Management. It was not excavated immediately due to their lack of resources at the time. In 1985, paleontologist David Gillette had finally been contracted to unearth the specimen. The holotype specimen consisted of vertebra, pelvis, and ribs. After 6 years of it residing in the New Mexico Museum of Natural History Gillette gave a name to the fossils. He called it "Seismosaurus halli", the species name honors Jim and Ruth Hall, a husband and wife team who ran the Ghost Ranch Museum and were good friends of Gillette. And Seismosaurus, the genus name literally means "Earthquake Lizard". However, since it was named after two people, Gillette's colleague George Olshevsky suggested making it "Seismosaurus hallorum". Gillette agreed and that was the name that was settled on for the next 15 years.
However, subsequent studies from 2006 and 2015 have regarded this animal as being a separate species of Diplodocus. The studies determined that there is no distinguishing anatomical difference between the Seismosaurus and Diplodocus aside from their size. Furthermore, the study in 2015 led by Emanuel Tschopp et.al found that most of the material belonging to the type species of Diplodocus, "Diplodocus longus" actually belongs to Diplodocus hallorum (other material that was assigned to D.longus is dubious or belongs to other Morrison sauropods). Thus, the animal has been reclassified as Diplodocus hallorum or Hall's Double-Beam.

Fossils:

Fossils attributed to this dinosaur have been found in Utah, Wyoming, and New Mexico. It would have shared the environment with Jurassic icons like Brontosaurus, Stegosaurus, and Camarasaurus. It also lived with a variety of predators like Allosaurus, Torvosaurus, and Ceratosaurus. These predators would have been more than capable of preying upon juvenile sauropods.

Size:

When it was first excavated, Diplodocus hallorum was thought to be one of the largest land animals that ever lived. Estimates ranged up to 180ft long and weighing as much as 100 tons.
However, it's now known that the size of these giants is vastly over-estimated. With bones filled with air-sacs, this animal likely was far lighter than previously thought. Perhaps ranging from 25 to 35 tons. Its size was based on more outdated methods of calculating size in dinosaurs. However, it was still a massive and awe-inspiring giant, roaming the fern prairies and scrubland of the Morrison Formation. With some individuals reaching lengths of over 100ft.

Habitat:

The environment of the Morrison Formation was a floodplain environment with lowland swamps and vast fern prairies with cycad and horsetail being the primary flora in the region. Conifers such as redwoods and monkey-puzzle trees are among the predominant conifer trees in the area. The trees and ferns would have been the primary browsing material for sauropods like Diplodocus and its kin. As far as how long these animals lived, they were only around for 2,000,000 years from 154-152,000,000 years ago, based on the rocks where the fossils were collected.

Rearing Behavior:

A trend commonly seen in Paleoart is sauropods rearing up on their hind legs to feed on taller trees. While definitely an awe-inspiring sight to behold in paleoart, was this actually possible for them to achieve? Recent studies have found support for this theory in most diplodocids across the board. For one, for a third of the way down the tail, bottom chevrons are strangely boat-shaped, perhaps used to provide support for the animal as it used its tail as a prop. Furthermore, the center of mass was placed near the hind limbs, an ideal position for the animal to rear up. So it's possible that these diplodocids could have reared up.

Diet:

Like all Sauropods in the Late Jurassic, Diplodocus hallorum was a herbivore. Its skull was equipped with peg-like teeth and they were believed to be used to strip plant material from horsetail, conifers, or ferns. Many paleontologists have theorized that diplodocids used unilateral branch stripping to feed. One row of teeth would grab the stem of the foliage, and the other would guide the stripping of the plants. They would then swallow down the plant matter and have it digest in their massive gut, no pre-processing of the food (chewing) would occur in the mouth. All processing of its food would occur in its massive gut.

Diplodocus hallorum is one of the largest sauropods that lived in the Morrison Formation. It remains an icon of the Jurassic, and one cannot deny the power and size of this magnificent creature.
___________________________________________________________________________________________

6/22: I updated it with a modified Barosaurus model and decided to bring it more in line for its appearance in the next episode of Past Meets Present as well as updated its statistics.

The main updates I made to the model were:
-A more fleshed out neck and head, where the flesh actually meshes from the neck into the head a lot better and doesn't have that shrink-wrapped look to it.
-Nostrils moved up to the front of the head.
-A resonation chamber.
-A more upright neck posture.
-Having spikes go all the way down to the tail.
-Finally, I added in claws onto its hands and feet. This is an aspect I have rarely seen done properly for Sauropods. The hands and feet are not just carbon copies of elephant limbs. The hand is hollow with most species having an enlarged claw outside forming a shape almost like a hoof. Whereas, the feet have 3 claws curving slightly to the side. This is something found on virtually every sauropod.

Furthermore, as much as I like the color scheme of the iconic WWD Diplodocus, I honestly cannot see a Sauropod having a bland, boring color scheme on its body. So I did a bit of modification to the skin, giving it a distinctive nose coloring and giving it stripes.

For more details on Sauropods, Darren Naish did an EXCELLENT blog post on the subject:
The Life Appearance of Sauropod Dinosaurs — Tetrapod Zoology (tetzoo.com)

For Past Meets Present:
Past Meets Present (Pt4 is Up) - Page 2 - The ZT2 Round Table

Original model by DinosaurManZT2 modified by me:
Diplodocus (HENDRIX) | ZT2 Download Library Wiki | Fandom