|Name Meaning||“Lizard of Memenchi”||Height||3-5 meters (9.5-16.4 feet) tall at the shoulder|
|Pronunciation||Mah-men-chee-sore-us||Length||15-35 meters (49.2-115 feet)|
|Era||Mesozoic – Late Jurassic–Early Cretaceous||Weight||5-80 tonnes (5.5-88.2 short tons)|
|Classification||Dinosauria, Saurischia & Sauropoda||Location||China (Asia)|
The Mamenchisaurus is most renowned for its unusually long neck.
You’ve heard it right! Its neck was remarkably long, even for a sauropod!
The lizard of Memenchi was first discovered in 1952 in China, and the following years brought to light new fossils, which led to the naming of six recognized species in the genus.
While they had a similar body shape, the species differed in size, weight, and temporal range, according to some specialists.
The Mamenchisaurus is among the few dinosaurs that lived in two periods, stretching from the Late Jurassic to the Early Cretaceous!
In this article, we’ll share everything you need to know about the sauropod, the famous long-necked sauropod – its appearance, distribution, behavior, and reproduction!
Although all Memenchisaurus specimens had a typical sauropod appearance, their size and skull characteristics differed slightly between species, so providing an exact length and weight would be quite challenging.
To get an overall understanding of their length and weight, we’ll discuss each species separately.
The type species, Mamenchisaurus constructus, likely measured approximately 13-15 meters (42.6-49.2 feet) long and weighed five metric tons (5.5 short tons). Only its neck measured 4.67 meters (15.3 feet) long!
Despite being the type species, it wasn’t the longest, as Mamenchisaurus hochuanensis was much larger, measuring 21-22 meters (69-72.2 feet) long.
Its neck was almost twice as long as the type species, reaching 9.3 meters (30.5 feet) long!
Things become more serious in terms of weight, as some specialists estimated it at 45 metric tons (49.6 short tons)! How unbelievable is this?
We certainly aren’t the only ones wondering about this, as other specialists rushed to lower the weight to 14-18.2 metric tons (15.4-20.1 short tons).
Mamenchisaurus anyuensis was roughly as long as M. hochuanensis, measuring 21-25 meters (69-82 feet) long and weighing 25 metric tons (27.5 short tons).
The same goes for Mamenchisaurus jingyanensis, which was 20-26 meters (65.6-85.3 feet) long and weighed approximately 12 metric tons (13.2 short tons).
If we judge by these numbers, we’d say that M. anyuensis was the heaviest of all.
Another species in the genus, Mamenchisaurus sinocanadorum, is thought to have measured 26 meters (85.3 feet) long, although other estimations go up to 35 meters (115 feet). Its weight was estimated at 60-80 metric tons (66.1-88.2 short tons)!
Mamenchisaurus youngi was just as small as the type species.
It was 16 meters (52.5 feet) long and weighed 7.87 tonnes (8.68 short tons). Its neck was only 6.5 meters (21.3 feet) long.
These sauropods were quadrupeds with large bodies, long tails, and small heads. Their shoulders were positioned slightly higher than their hips.
They had distinctive chevrons on their tails that likely helped in weight distribution.
Some scientists think the Mamenchisaurus had a tail club consisting of the neural spines extending from the fused caudal vertebrae at the tip of the tail.
It has also been suggested that it had the shortest legs among all known sauropods.
Habitat and Distribution
Most Mamenchisaurus fossils were recovered from the following locations:
- Shaximiao Formation, Sichuan, China
- Shishugou Formation, Xianjian, China
- Suining Formation, Sichuan, China
- Penglaizhen Formation, Sichuan, China
During the Jurassic, the world was much warmer than today, typically registering temperatures higher by 5-10 degrees Celsius (41-50 degrees Fahrenheit).
Approximately 164 million years ago, the Kimmeridgian Warm Interval started and lasted for 16 million years.
The Mamenchisaurus was alive back then and probably felt these changes.
This warm period is believed to have been extremely wet – the wettest of the Jurassic.
By the end of the Jurassic, however, Mamenchisaurus likely had to survive extreme weather changes, as 150 million years ago, the Late Jurassic registered the Tithonian-early Barremian Cool Interval, which continued into the Early Cretaceous.
After the first stage of the Early Cretaceous, the world started warming up again.
China’s Sichuan Basin was surrounded by mountains, which ensured a foggy habitat.
The territory featured four seasons, including hot and humid summers and cool winters.
The exact temperatures vary depending on specific locations. Overall, the climate was likely humid and subtropical.
The Shaximiao Formation, which hosted most Mamenchisaurus fossils, is thought to have been a lush forest crossed by a lake that was, in turn, fed by a large river.
As such, the lake swept the fossils, which is why the area is now abundant in them.
The Shishugou Formation was a marshland surrounded by a small mountain range and several volcanoes.
Behavior and Diet
While the Mamenchisaurus was fully quadrupedal, it has been suggested that it could walk very slowly in a bipedal mode.
This is indicated by the hip bones, which were retroverted and thus allowed slow bipedal walking.
A tripodal stance was also likely possible, meaning it stood on two legs and was supported by its tail, which would act as a prop, while the forked chevrons that start in the middle of the tail would ensure even weight distribution.
A study shows that the Mamenchisaurus could keep its neck vertical and raise its head above the shoulders.
However, as with other sauropods, the neck posture is highly debated; some specialists believe it could hold its neck only horizontally, while others argue the neck were flexible enough to be lifted upward.
For example, a study on Mamenchisaurus youngi revealed that its neck was likely almost straight and only slightly bent upward at the base, while the head was slightly bent downward.
Supposedly, it might have been able to raise its neck upward but not downward at the base. Near the head, it was more flexible for downward than upward movements.
The middle of the neck was more flexible for downward movements, which indicates that feeding was done only on low bushes or trees.
As we’ve already mentioned, the Mamenchisaurus probably had a tail club, which may have served as a defensive weapon and a sensory organ.
However, even if used against predators, the tail club likely wasn’t effective, as it was not strong enough to hurt opponents or survive trauma.
You’ve probably already guessed that Mamenchisaurus sauropods were herbivorous. However, it is unknown precisely what types of plants they feed on.
It had been confirmed that juveniles and adults had different diets (based on tooth wear), and they likely fed together in age-segregated herds.
The Mamenchisaurus reproduced by laying eggs. Unlike birds, which have only one functional oviduct and, thus, lay only one egg at a time, the females had two functional oviducts and laid two eggs at a time.
Hatching occurred approximately 65-82 days after egg-laying.
It remains unknown what kind of nesting and incubating behavior sauropods engaged in.
Since most baby dinosaurs were precocial, meaning they did not require much adult help once hatched, scientists argue this was also valid for sauropods.
Some specialists argue in favor of age-segregated herds for sauropods.
Despite this, the adults probably didn’t show too much parental care.
Studies on some Mamenchisaurus specimens revealed that death occurred when they were approximately 43 years old.
Evolution and History
The Sauropoda clade contains the world’s biggest terrestrial vertebrates.
So how did they grow so large? What did sauropods evolve from?
Sauropods, including Mamenchisaurus, evolved from smaller, bipedal creatures.
As they continuously evolved, so did their size and shape. Over the years, they became larger and heavier.
The oldest known sauropods date from the Early Jurassic and are considered members of the Isanosaurus and Antetonitrus genera.
The Isanosaurus, for example, was much smaller than the sauropods that followed it, measuring only 6.5 meters (21.3 feet) long.
The same is valid for the Antetonitrus, which measured 8-10 meters (26.3-32.8 feet) in length.
By the Late Jurassic, meaning when Mamenchisaurus was alive, sauropods were already widely spread worldwide.
The first Mamenchisaurus fossils were discovered quite recently – that is if we compare the discovery with other dinosaur discoveries.
It occurred in 1952 in China’s Sichuan province.
Paleontologists unearthed a partial skeleton attributed to Mamenchisaurus constructus two years later.
In 1972, a second species was described – Mamenchisaurus hochuanensis.
It was followed by Mamenchisaurus sinocanadorum in 1993, although it was redescribed in 2023.
1996 brought the description of yet two other species – Mamenchisaurus anyuensis and Mamenchisaurus youngi.
Two years later, scientists named and described a sixth species, Mamenchisaurus jingyanensis.
Other species were named over the years but are now considered dubious.
Even the recognized ones are often questioned, especially the type species, as many scientists argue it wasn’t studied enough to understand the genus.
These giants were once placed in the Euhelopodidae family alongside Euhelopus, Erketu, and Tangvayosaurus.
However, today, the genus is placed under the Mamenchisauridae family under the Eusauropoda clade.
Other members of this family, and thus, close relatives of the Mamenchisaurus, include the Klamelisaurus, Huangshanlong, Xinjiangtitan, and Yuanmousaurus.
Interactions with Other Species
The members of the Mamenchisaurus genus are thought to have lived in different periods.
For example, Mamenchisaurus sinocanadorum likely lived during the Oxfordian, while Mamenchisaurus anyuensis probably lived during the Aptian, leaving a gap of approximately 50 million years between them.
As such, it would be quite challenging to list all the creatures they stumbled upon, as this depends on what species we’re discussing and its temporal range.
We’ve prepared a list of possible creatures the Mamenchisaurus shared its habitat with, but remember that there’s no absolute certainty about it:
- Crocodyliformes like Sunosuchus and Hsisosuchus
- Pterosaurs like Sericipterus
- Ornithischians like Gigantspinosaurus, Chungkingosaurus, Tuojiangosaurus, and Gongbusaurus
- Sauropods like Shunosaurus and Zigongosaurus
Mamenchisaurus lived in an ecosystem filled with other herbivores.
Scientists argue that each species had specialized feeding behaviors and techniques that allowed peaceful cohabitation.
This can’t be said about carnivorous theropods as well.
After all, it is well known that theropods delighted in some sauropod meals.
Although the theropods living in the area were likely smaller than the famous carnivorous T-Rex, it is well-known that they had well-developed hunting techniques that allowed them to subdue large prey, including sauropods.
However, if Mamenchisaurus sauropods moved in herds, as some scientists suggest, the likelihood of a small theropod killing them is very low.
The study of Mamenchisaurus is of major significance in the paleontological world, as the fossilized specimens carry essential information about the evolution of mamenchisaurids, sauropods, and dinosaurs.
Despite its importance in our world’s evolutionary history, the Mamenchisaurus isn’t as popular in the media as other sauropods.
However, Jurassic Park fans have probably already spotted the Mamenchisaurus creatures in The Lost World: Jurassic Park.
Apart from this brief appearance, the Mamenchisaurus is not a favorite among creators.
Renowned for its remarkably long neck and incredible size, the Mamenchisaurus was a Chinese dinosaur that lived from the Late Jurassic until the Early Cretaceous.
The genus now consists of six species known from multiple specimens recovered from China.
The members of the genus varied in size and weight, ranging from 15 to 35 meters (49.2-115 feet) long and 5 to possibly 80 tonnes (5.5-88.2 short tons).
Mamenchisaurus individuals likely moved in herds and fed on low vegetation.
They shared their habitats with herbivorous, carnivorous, and omnivorous dinosaurs, as well as other prehistoric creatures like turtles, pterosaurs, and crocodyliforms.
Is Mamenchisaurus the biggest dinosaur?
While Mamenchisaurus was the largest sauropod discovered in China and one of the biggest terrestrial creatures, it would be impossible to state if it was the largest dinosaur ever, as size estimations aren’t fully confirmed yet.
Did the Mamenchisaurus have the longest neck?
Mamenchisaurus dinosaurs are thought to have had the longest necks, ranging from 6.5 to 15.1 meters (21.3-49.5 feet) long.