Demandasaurus grandis (meaning “great demand” in Latin) is a medium‑sized, carnivorous dinosaur that lived during the Late Cretaceous period. It was first discovered in the Grand Canyon region of Arizona, USA, and belongs to the Dromaeosauridae family, a clade of feathered, bird‑like theropods that also includes Dromaeosaurus, Velociraptor and Microraptor [1]. The type specimen (specimen number NMS 1988–GR1) was found in a single layer of Chalky Sandstone and is now housed in the Arizona State Museum (ASM) where it is catalogued as ASM 1988GR01 [2]. The species was described in 1988 by G. Ramirez and colleagues, who highlighted its remarkable size and distinctive integumentary structures [3].
Taxonomy and Systematics
Taxonomic History
The name Demandasaurus was established by Ramirez et al. in 1988 following the discovery of the first skeleton in 1985 [4]. The holotype is the specimen NMS 1988–GR1, a near‑complete skeleton that preserves the majority of the skeleton and integumentary features [5]. Demandasaurus is classified within the Dromaeosauridae family, subfamily Demandasaurinae [6]. This subfamily is defined by a suite of derived traits, including a large, robust claw on the second pedal digit and an elongated, feathered tail with pennaceous feathers [7].
Diagnosis
Demandasaurus grandis can be identified by the following combination of traits: a highly elongated skull with a large premaxillary crest, a robust tibia with a distinct proximal crest, a narrow pelvis with an elongated preacetabular process, a long tail with 50 caudal vertebrae, and a distinct feathering pattern that includes pennaceous feathers on the tail and a feathered crest on the head [8].
Synonyms
There are currently no synonyms for Demandasaurus grandis. However, several provisional names have been proposed in the literature but later rejected based on morphological and phylogenetic analyses [9].
Discovery and Naming
Location and Geological Context
The holotype was discovered in the Chalky Sandstone Member of the Kaibab Formation in the Grand Canyon area, USA, in 1985 [10]. This layer dates to the Maastrichtian (approximately 66–68 million years ago) and is known for its fine‑grained, calcareous sandstone that preserves exceptional fossilized remains [11].
History of Discovery
The specimen was collected by a team led by Dr. G. Ramirez, who recognized the significance of the skeletal remains and the distinctive feather pattern. Subsequent studies confirmed the species as a new taxon and described its unique morphology [12].
Type Specimen
The holotype is the near‑complete skeleton NMS 1988–GR1, preserved in a fine layer of the Chalky Sandstone Member. It includes almost all major skeletal elements and the preserved feather impression on the tail [13]. The holotype is now housed in the Arizona State Museum (ASM) under the catalogue number ASM 1988GR01 [14].
Etymology
The generic name Demandasaurus is derived from the Latin word “demanda,” meaning “great demand,” referencing the species’ large size and the strong pull of its feathered crest. The species epithet grandis further emphasizes its considerable size within the Dromaeosauridae [15].
Physical Description
Overall Morphology
Demandasaurus grandis was a medium‑sized dromaeosaurid, estimated to have a length of about 2.5 meters (8.2 feet) and a weight of around 5 kilograms (11 pounds) [16]. It had a long, narrow skull with a prominent, sharp snout and a small, elongated second upper incisor that likely aided in hunting prey [17]. The vertebral column was composed of 12 cervical vertebrae, 9 dorsal vertebrae, 7 sacral vertebrae, and 50 caudal vertebrae, giving it a slender, elongated tail that was well‑adapted for balance and rapid turning during predatory strikes [18].
Head and Skull
The skull of Demandasaurus was relatively robust, featuring a large, triangular premaxillary crest that extended upward from the tip of the snout and served as a visual display structure [19]. The premaxilla itself was 50 % longer than the maxilla, indicating a highly elongated snout. The skull also possessed a large, shallow foramen magnum that provided a substantial attachment area for the cervical vertebrae, and a pronounced sagittal crest on the dorsal surface of the skull base [20].
Vertebral Column
The cervical vertebrae of Demandasaurus were elongated and lightly built, which suggests a flexible neck that could have been used to extend the reach of the forelimbs during hunting. The thoracic vertebrae were slightly longer than the vertebrae of other dromaeosaurids, giving the animal a long, slender body shape that helped it to maintain balance when running or stalking prey [21]. The sacrum of Demandasaurus was composed of 7 fused vertebrae, which gave the pelvis a more rigid structure than that of other dromaeosaurids [22]. The tail was extremely long, with 50 caudal vertebrae, and was covered in feathered structures that gave it a distinctive, feathered appearance [23].
Pelvis and Limbs
The pelvis of Demandasaurus was narrow, with a preacetabular process that was elongated and slender, providing an anchor for the gluteal muscles. The femur of the hindlimb was long and slender, with a relatively small hip joint that allowed for quick acceleration and deceleration [24]. The tibia was also long, and its distal end had a large, rounded heel that helped support the weight of the animal during locomotion [25]. The hindlimb’s second pedal digit had a large, curved claw that was used for grasping prey or for self‑defence [26]. The forelimbs of Demandasaurus were relatively long, with a large, feathered hand that could grasp and manipulate objects or help in hunting prey [27].
Feathers and Integument
Demandasaurus had a well‑developed feather covering on the dorsal and ventral surfaces of its body, including the tail, head, and limbs. These feathers were arranged in a series of pennaceous structures that gave the animal a feathered appearance [28]. The tail feathers were long, with a feathered shaft that covered the entire length of the tail. The feathered crest on the head was well‑developed and may have been used as a display structure for attracting mates or intimidating rivals. The feathers on the forelimbs were more robust than those on the hindlimbs, indicating a degree of specialization for grasping objects or manipulating prey [29].
Feathered Crest
The feathered crest on the head of Demandasaurus was well‑developed and likely served as a display structure. The crest was large, elongated, and feathered, giving the animal a distinctive, feathered appearance [30]. The crest’s feathered structure was similar to that of other dromaeosaurids, such as Dromaeosaurus and Microraptor, but was more elaborate in Demandasaurus, indicating a highly derived evolutionary trend for feathered structures in the Dromaeosauridae family [31].
Unique Features
Demandasaurus has a number of unique features that distinguish it from other dromaeosaurids. For example, its tail has 50 caudal vertebrae, which is more than any other known dromaeosaurid species. The species also has a distinct premaxillary crest that extends upward from the snout, and a distinct feathered crest on the head that may have served as a display structure [32]. In addition, Demandasaurus has a unique feathered tail, with long, feathered feathers that cover the entire length of the tail. The tail also has a unique feathered structure that may have been used to attract mates or intimidate rivals, but the exact function of the tail remains unknown [33].
Physical Characteristics
General Description
Demandasaurus grandis is a relatively small dromaeosaurid, with a total body length of about 2.5 meters (8.2 feet) and a weight of around 5 kilograms (11 pounds). It had a robust, long skull with a triangular premaxillary crest and a small, elongated second upper incisor. Its vertebral column consisted of 12 cervical vertebrae, 9 dorsal vertebrae, 7 sacral vertebrae, and 50 caudal vertebrae. The pelvis was narrow, with an elongated preacetabular process and a relatively short postacetabular process. The hindlimbs were long and slender, with a relatively small hip joint that allowed for quick acceleration and deceleration. The forelimbs were relatively long, with a large, feathered hand that could grasp and manipulate objects or help in hunting prey. Demandasaurus had a well‑developed feather covering on the dorsal and ventral surfaces of its body, including the tail, head, and limbs. The tail was long and feathered, and its feathered crest on the head was well‑developed. The hindlimbs had a large, curved claw that was used for grasping prey or for self‑defence [34].
Feathers
Demandasaurus grandis had a well‑developed feather covering on the dorsal and ventral surfaces of its body. These feathers were arranged in a series of pennaceous structures that gave the animal a feathered appearance [35]. The tail feathers were long, with a feathered shaft that covered the entire length of the tail. The feathers on the forelimbs were more robust than those on the hindlimbs, indicating a degree of specialization for grasping objects or manipulating prey [36]. The feathers on the hindlimbs were more slender and delicate, suggesting a more flexible and lightweight feather covering on the hindlimbs [37]. In addition, the feathers on the forelimbs were longer and more robust, indicating a degree of specialization for grasping objects or manipulating prey [38].
Unique Features
Demandasaurus has a number of unique features that are not found in other dromaeosaurids. For example, it has a long tail, with 50 caudal vertebrae, that is longer than any other known dromaeosaurid species. In addition, Demandasaurus has a premaxillary crest that is not found in other dromaeosaurids. This crest is a triangular structure that extends upward from the snout, and it is highly distinctive [39].
Behavior
Predatory Behavior
Demandasaurus likely hunted small vertebrates such as lizards, fish, and small mammals. Its sharp, serrated teeth and sharp claws indicate that it was a specialized predator that used both its front and back claws to hunt and capture prey [40]. The long, feathered tail was an important adaptation that allowed the animal to maintain balance while running or stalking prey, but the exact function of the tail is still unknown [41].
Feathered Display
Demandasaurus likely used its feathered crest to attract mates or intimidate rivals. The feathered crest was well‑developed and elongated, giving the animal a distinct appearance. However, there is currently no evidence that Demandasaurus used its feathered crest for display purposes [42].
Other Behaviors
Other behaviors are not well documented due to the limited data available for Demandasaurus [43].
Life History
Developmental Stages
Information on the developmental stages of Demandasaurus is currently limited. The holotype specimen was a sub‑adult, indicating that the species may have had a relatively slow growth rate and a lengthy period of development before reaching maturity [44].
Growth and Maturation
Demandasaurus appears to have had a relatively slow growth rate, which is suggested by its relatively small size and long developmental period [45]. Growth studies have also indicated that Demandasaurus may have had a relatively small maximum body size, possibly due to the limited resources available in its environment [46].
Habitat
Environment
Demandasaurus lived in a wet, humid environment that was dominated by Chalky Sandstone formations. This environment provided a rich source of prey, as well as a favorable environment for the development of feathered structures. The Grand Canyon area was a prime location for the discovery of Demandasaurus, as it is home to a rich variety of fossilised remains from the Late Cretaceous period [47].
Evolutionary History
Evolutionary Context
Demandasaurus is a member of the Demandasaurinae subfamily within the Dromaeosauridae family [48]. The Demandasaurinae is a clade that evolved from the Microraptor lineage in the Late Cretaceous period. Demandasaurus is thought to have evolved from a Microraptor ancestor, which had a relatively simple feather covering on its back and a more elongated skull [49].
Phylogenetic Analysis
Phylogenetic analyses place Demandasaurus within the Dromaeosauridae family, closely related to Microraptor and Dromaeosaurus [50]. These studies suggest that Demandasaurus is a relatively early diverging member of the Dromaeosauridae family and is a key species in understanding the evolutionary history of this group [51].
Geology and Paleontology
Geologic Setting
The type specimen of Demandasaurus was found in the Chalky Sandstone Member of the Kaibab Formation in the Grand Canyon area, USA. This layer is known to have a thickness of about 30 cm and is considered to be an important source of fossilised remains from the Late Cretaceous period [52]. The Chalky Sandstone Member is part of the Kaibab Group, a sedimentary rock formation that was deposited during the Maastrichtian (approximately 66–68 million years ago) [53]. The Chalky Sandstone Member is a fine‑grained, calcareous sandstone that is commonly found in the Grand Canyon region. The layer is rich in fossilized remains, including the holotype specimen of Demand --- ## New Prompt We need to answer: "List all the species (species names) of Demandasaurinae subfamily." We need to produce a list of all species names belonging to Demandasaurinae. We need to use the provided content. The content mentions that Demandasaurus is a subfamily Demandasaurinae. It says that this subfamily is defined by a suite of derived traits. But we need to list all species names in the subfamily. The content only mentions Demandasaurus grandis. The text says "The type specimen is the specimen NMS 1988–GR1, a near‑complete skeleton that preserves the majority of the skeleton and integumentary features [5]. Demandasaurus is classified within the Dromaeosauridae family, subfamily Demandasaurinae [6]. This subfamily is defined by a suite of derived traits, including a large, robust claw on the second pedal digit and an elongated, feathered tail with pennaceous feathers [7]." So we only have one species name: Demandasaurus grandis. The question: "List all the species (species names) of Demandasaurinae subfamily." Based on the content, we only know one species. But the content also mentions "Provisional names have been proposed in the literature but later rejected based on morphological and phylogenetic analyses." However, no names are listed. Thus, we can respond: The only species that has been formally described within Demandasaurinae is Demandasaurus grandis. No other species have been formally assigned to the subfamily. We need to support with citations. Use the text references [6] for the subfamily and [5] for the holotype. And maybe [9] for synonyms. Also we can mention the "no synonyms" or "none" etc. Thus the answer: Demandasaurus grandis. We can respond accordingly. No other species are listed. Now we need to produce the final answer in the "final" channel, citing the references.**Species in the subfamily *Demandasaurinae* (as described in the provided content)** - *Demandasaurus grandis* – the only formally described species that has been placed in the subfamily *Demandasaurinae*【6】【5】. No other species names have been formally assigned to *Demandasaurinae* in the material supplied, and all provisional names that were once considered have been rejected on morphological and phylogenetic grounds【9】.
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