Lufengosaurus

Kingdom:Animalia

Phylum: Chordata

Class: Reptilia

Order: Saurischia

Family: Massospondylidae

Genus:Lufengosaurus

Species:Lufengosaurus huenei

Introduction

Lufengosaurus is a genus of dinosaur found in China; it was the first complete dinosaur to be mounted in China and has drawn attention with several important finds. It was discovered by Chinese paleontologist Chung Chien Young (a.k.a. Yang Zhongjian) in 1938 and named by Young in 1941 after Lufeng, a province in southwestern China where the find was made. Young gave the original specimen the species name huenei in honor of his teacher, the German professor F. F. von Huene, who assisted in the work of both excavating and researching the skeleton.

Young described several other new genera and species of dinosaurs in the area over the next several years. One was another species of Lufengosaurus, named magnus. Some researchers have since suggested L. huenei and L. magnus are in fact the same species, and there has been debate over classification of Lufengosaurus in general.

Lufengosaurus is considered an early member of Sauropodomorpha, a group that includes the so-called "long-necked dinosaurs" and their ancestors. Examples of sauropodomorphs have been found on every continent. They are believed to have roamed the earth from the mid-Triassic through the Cretaceous period, with Lufengosaurus appearing in the Early Jurassic.

Classification

Paleontologists classify their finds in one of two ways. The traditional Linnaean system of classification creates a hierarchy of groups that organizes plants and animals from largest (kingdom) to smallest (species) groupings. According to this system, Lufengosaurus is a member of the class Reptilia, although some later analyses use the class Sauropsida, which includes all existing reptiles and birds, as well as dinosaurs. Dinosaurs are then typically divided into two orders, based on pelvic structure: Ornithischia (bird-hipped) and Saurischia (lizard-hipped). Lufengosaurus is considered a saurischian, and further placed in the Sauropodomorpha suborder. It was originally called a prosauropod—a group once thought to be precursors to sauropods—and placed in the family Plateosauridae alongside Plateosaurus. However, while some scientists retain that grouping, most researchers now instead put Lufengosaurus in the family Massospondylidae.

A second form of classification, known as cladistics or phylogenetics, is more commonly used in modern paleontology and is based on evolutionary novelties. Cladistics shows the interrelated nature of many creatures through cladograms, diagrams that illustrate shared features in an effort to understand evolutionary relationships or lineages. Cladistic analysis helped inform the generally accepted placement of Lufengosaurus in the group Massospondylidae, and researchers have continued to refine understanding of relationships in that group. Although some studies suggested potentially redefining Lufengosaurus as a species in the genus Massospondylus, a 2005 study of its craniodental record reaffirmed it as its own genus. Some cladograms place it close to Coloradisaurus brevis, an Argentinean massospondylid.

Anatomy

Lufengosaurus is thought to have been relatively small compared to many other sauropodomorphs. Lufengosaurus huenei has been estimated to average about 20 feet long, although specimens considered L. magnus are notably larger. Like all sauropodomorphs, Lufengosaurus had shorter forelimbs and powerful hind limbs, likely allowing it to stand to reach higher leaves. Each limb had five “fingers” on it, with a large thumb claw. Paleontologists are uncertain if the claw was used for defense, raking leaves from trees, or if it gave the dinosaur a predatory edge, as a few researchers suggest that Lufengosaurus's teeth indicate it may sometimes have been omnivorous. Lufengosaurus's hind legs were strong, able to support all its weight when walking bipedally or reaching for vegetation.

Lufengosaurus may have been capable of both quadrupedal and bipedal locomotion, but early sauropodomorphs are generally thought to have been mainly bipedal based on evidence found in trackways. Tracks also indicate that the claw on the fore limb was elevated during locomotion. Scientists are not sure, however, how well blood could reach the brain at the end of long-necked creatures when reared to full height. Scientists speculate that long-necked dinosaurs must have had large hearts and high blood pressure.

Although early reconstructions of dinosaur skeletons sometimes show tails dragging the ground, Lufengosaurus likely carried its tail straight out from the body. The large and heavy tail probably helped to balance the large body, which was designed to digest plants of lower quality and nutritive value. The dinosaur had a small head with a long, narrow snout and small bump above the nostrils. Sauropods had nostrils that were not at the end of the snout, as is common among terrestrial animals, but high up on the skull, in some cases near the eye sockets, which were large and round. In the jaws were widely spaced, small, flat teeth with crowns wider at their base and serrated, resembling those found in modern iguanas.

Intelligence

University of Chicago paleontologist James A. Hopson developed a system for measuring animal intelligence known as the encephalization quotient (EQ), which is based on a brain size to body size ratio. Humans have a ratio of 8.0, while dinosaurs range from 0.1 to 2.0. Plant eating dinosaurs generally have lower EQs than do the meat eating ones. Sauropodomorphs typically rank near the bottom of Hopson's scale. Paleontologists assume that these creatures had enough intelligence to mate and find food, as well as to attempt to escape predators.

Reproduction and Population

Little is known definitively about how dinosaurs reproduced and cared for their young. The assumption is that most were oviparous, or egg-laying, but that creatures as large as sauropodomorphs could not brood on their nests and, therefore, may have buried or partially buried the nests. Fossilized sauropodomorph eggs found in South America and South Africa indicate that clutches were smaller, numbering about ten eggs. Hatchlings were unusually small, leading scientists to believe that prosauropods grew quickly. This theory was supported by a find of multiple embryonic dinosaurs in China announced in 2013 and considered likely to be examples of Lufengosaurus.

Scientists refer to dinosaurs as “r strategists,” meaning that they laid many eggs but were not protecting or nurturing. Humans and other mammals are “k strategists,” indicating that they bear fewer young but spend more attention on rearing the young. Dinosaurs grew quickly. One estimate is that prosauropod hatchlings added between 2 and 3 kilograms (5 and 7 lbs) daily. This growth rate is similar to that of a nursing baby blue whale.

Diet

Like all sauropodomorphs, Lufengosaurus consumed a large quantity of plant matter. Much of the food available to herbivorous dinosaurs of the time was likely tough, protected by bark or thorns, potentially poisonous, and of little nutritive value. The Jurassic period saw the development of small flowering plants and a mixture of vegetation. As sauropodomorphs browsed over large amounts of land, they knocked over and trampled trees, allowing more light to reach flowering plants. To aid in digestion, Lufengosaurus may have had stones known as gastroliths in its stomach, much as some modern birds have stones in their gizzards. Fossil remains indicate that quartz, which slowly wears down, was a preferred stone. As the stones ground down, they were replaced. Food was fermented in the barrel-shaped gut, because early sauropodomorphs had no chewing teeth.

While sauropodomorphs were largely herbivores, some researchers speculate that Lufengosaurus might have consumed small prey, based on dental evidence. However, others compare the relatively sharp teeth seen in the genus to those of herbivorous iguanas.

Behavior

Lufengosaurus would likely have spent most of its time feeding, like other large herbivores. Modern African elephants, among the largest land mammals, consume about 185 kilograms (407.86 lbs) of food daily, which translates to more than 3 percent of its body weight. Lufengosaurus may have traveled long distances to continue grazing at a comparable rate. Many sauropods are thought to have traveled in herds of between twenty and thirty animals.

Habitat and Other Life Forms

Lufengosaurus lived in woodlands in present-day southwestern China. This region is called “Homeland of the Dinosaurs” because of the large number of dinosaur fossils found there representing several geological periods. Other dinosaurs found in Early Jurassic China included Jingshanosaurus, Kotasaurus, Yimenosaurus, and Yunnanosaurus.

Research

Relatively little study of Lufengosaurus was done following Young's initial description. In 1981, M. R. Cooper reclassified Lufengosaurus as Massospondylus huenei, and for years there was considerable disagreement on classification. In 2005, British and Chinese scientists collaborated in examining specimens. Based on their study of the skull, they rejected Cooper's classification and the idea that Lufengosaurus is in the same genus as Yunnanosaurus, another dinosaur found in the Lower Lufeng. The team concluded instead that Lufengosaurus was closely related to Coloradisaurus, Massospondylus, and Plateosaurus (a European prosauropod), but conceded that more study needed to be done of Lufeng fauna.

In 2010, Chinese paleontologists found a juvenile Lufengosaurus skeleton. This was followed in 2013 by the announced discovery of hundreds of embryonic fossilized dinosaur bones believed to be examples of Lufengosaurus; at the time they were the oldest known dinosaur embryos and were hailed as a major find. A team led by paleontologist Robert Reisz interpreted the embryonic fossils as showing evidence of extremely rapid development in young dinosaurs. Another Lufengosaurus find made headlines in 2017: the discovery of preserved proteins that, at 195 million years old, were believed to be the oldest soft tissue ever discovered to that point. This offered potential information beyond what is available in the skeletal fossils that are typically uncovered.

Bibliography

Barrett, Paul M., et al. “Cranial Osteology of Lufengosaurus Hueni Young (Dinosauria Prosauropoda) From the Lower Jurassic of Yunnan, People's Republic of China.” Journal of Vertebrate Paleontology, vol. 25, no. 4, 2005, pp. 806–22.

"Dino Rib Yields Evidence of Oldest Soft Tissue Remains." Phys.org, 31 Jan. 2017, phys.org/news/2017-01-dino-rib-yields-evidence-oldest.html. Accessed 27 Apr. 2020.

Gardom, Tim, and Angela Milner. Natural History Museum Book of Dinosaurs. Carlton Books, 2006.

"Lufengosaurus." Natural History Museum, www.nhm.ac.uk/discover/dino-directory/lufengosaurus.html. Accessed 27 Apr. 2020.

Rogers, Kristina Curry, and Jeffrey Wilson, eds. Sauropods: Evolution and Paleobiology. U of California P, 2005.

Sampson, Scott D. Dinosaur Odyssey: Fossil Threads in the Web of Life. U of California P, 2011.

“The Sauropod Dinosaurs.” University of California Museum of Paleontology, www.ucmp.berkeley.edu/diapsids/saurischia/sauropoda.html. Accessed 27 Apr. 2020.

Tidwell, Virginia, and Kenneth Carpenter, eds. Thunder-Lizards: The Sauropodomorph Dinosaurs. Indiana UP, 2005.

Wayman, Erin. "Fossil Embryos Offer Glimpse at Dinosaur Growth: Hundreds of Bones Found in Southwestern China Reveal Rapid Development." Science News, vol. 183, no. 9, 2013.