Pelecanimimus
Encyclopedia
Pelecanimimus is a genus
of basal
("primitive") ornithomimosaurian theropod dinosaur
from the Early Cretaceous
of Spain
. It is notable for possessing more teeth than any other member of the Ornithomimosauria
(or any other theropod), most of which were toothless.
pelecanus, "pelican", and mimus, "mimic", in reference to the long snout and throat pouch. The specific name is a reference to the large number of teeth possessed by this theropod and is derived from Greek πολύς (polys), "many" and ὀδούς (odous) "tooth".
The holotype
specimen, LH 7777, part of the Las Hoyas Collection presently housed at the Museo de Cuenca, Cuenca
, Spain
, of Pelecanimimus was recovered at the famous La Hoyas locality in Cuenca Province, Spain, from lagerstätte
beds within the Calizas de La Huérguina Formation dating to the Lower Barremian
.
The only known specimen consists of the articulated front half of a skeleton and includes the skull, lower jaws, all the neck vertebrae and most of the back vertebrae, ribs, sternum
, the pectoral girdle, a complete right forelimb and most of the left forelimb. Remains of the soft parts are visible at the back of the skull, around the neck and around the front limbs.
ry teeth, about thirty maxilla
ry, and seventy-five in the dentary. The teeth were heterodont
, showing two different basic forms. The teeth in the front of the upper jaw were broad and D-shaped in cross-section, while those further back were blade-like, and on the whole the teeth in the upper jaw were larger than those in the lower. All of its teeth were unserrated, and had a constricted "waist" between the crown and the root. Interdental plates were lacking.
Only one other ornithomimosaur is known to possess teeth, Harpymimus
, which had far fewer (eleven total, and only in the lower jaw). The presence of such a large number of teeth in Pelecanimimus, coupled with a lack of interdental space, was interpreted by Pérez-Moreno et al. as an adaptation
for cutting and ripping, a "functional counterpart of the cutting edge of a beak
," as well as an exaptation
leading to the toothless cutting edge found in later ornithomimosaurs.
The arms and hands of Pelecanimimus were more typical of ornithomimosaurs, with the ulna
and radius
bones in the lower arm tightly adhered to each other. The hand was hook-like and had fingers of equal length equipped with rather straight claws.
Soft-tissue remains preserved by the exceptional preservational environment of the La Hoyas lagerstätte revealed the presence of a small skin or keratin crest on the back of the head, and a gular pouch similar to the much larger pouches found in modern pelicans, from which Pelecanimimus took its name. Pelecanimimus might have been much like a modern day crane, wading out in lakes or ponds using its claws and teeth to capture fish and then storing them in its skin flap. Some parts of the impressions revealed wrinkled skin, interpreted as lacking scales or feathers. Filament-like structures were also preserved; first interpreted as an integument, these were later seen as representing preserved muscle fibers. Pelecanimimus was also the first ornithomimosaur discovered with a preserved hyoid apparatus (specialized tongue bones in the neck).
of the Ornithomimosauria. To quote Pérez-Moreno et al., "The phylogenetic hypothesis...supports an unexpected approach, involving exaptation, which might explain the evolutionary process towards the toothless condition in Ornithomimosauria. Until now, a progressive reduction in the number of teeth has been considered as the most likely explanation: the primitive tetanurine
theropods have up to 80 teeth with tall blade-like crowns, and the primitive ornithomimosaurs have only a few small teeth. The phylogenetic hypothesis suggests an alternative evolutionary process based on a functional analysis of increasing numbers of teeth. A high number of teeth with enough interdental space and properly placed denticles (as in troodontids) would be an adaptation for cutting and ripping. On the other hand, an excessive number of teeth with no interdental space (as in Pelecanimimus) would be a functional counterpart of the cutting edge of a beak. Thus, increasing the number of teeth would be an adaptation for cutting and ripping, as long as the space between adjacent teeth was preserved...while it would have the effect of working as a beak if spaces were filled with more teeth. The adaption to a cut-and-rip function therefore becomes an exaptation with a slicing effect, eventually leading to the cutting edge seen in most ornithomimosaurs."
Cladogram
after Kobayashi and Lü, 2003:
Ornithomimosauria
|--Pelecanimimus
`--o--Harpymimus
`--o--Garudimimus
`--Ornithomimidae
birds Iberomesornis
, Concornis
, and Eoalulavis
, along with non-avian
theropod teeth and a few fragmentary sauropod bones. Coarse sediments of the La Hoyas lagerstätte have produced bones of the ornithopod
dinosaur Iguanodon
. The lagerstätte beds have also yielded remains of lizard
s and salamander
s.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
("primitive") ornithomimosaurian theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
. It is notable for possessing more teeth than any other member of the Ornithomimosauria
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
(or any other theropod), most of which were toothless.
Discovery and naming
In July 1993 Armando Díaz Romeral discovered a theropod skeleton at the Las Hoyas Unit 3 site. In 1994 this was named and described by Bernardino Pérez Pérez-Moreno, José Luis Sanz, Angela Buscalioni, José Moratalla, Francisco Ortega and Diego Rasskin-Gutmanas as a new species: Pelecanimimus polyodon. The generic name is derived from LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
pelecanus, "pelican", and mimus, "mimic", in reference to the long snout and throat pouch. The specific name is a reference to the large number of teeth possessed by this theropod and is derived from Greek πολύς (polys), "many" and ὀδούς (odous) "tooth".
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen, LH 7777, part of the Las Hoyas Collection presently housed at the Museo de Cuenca, Cuenca
Cuenca, Spain
-History:When the Iberian peninsula was part of the Roman Empire there were several important settlements in the province, such as Segóbriga, Ercávica and Gran Valeria...
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, of Pelecanimimus was recovered at the famous La Hoyas locality in Cuenca Province, Spain, from lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
beds within the Calizas de La Huérguina Formation dating to the Lower Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
.
The only known specimen consists of the articulated front half of a skeleton and includes the skull, lower jaws, all the neck vertebrae and most of the back vertebrae, ribs, sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...
, the pectoral girdle, a complete right forelimb and most of the left forelimb. Remains of the soft parts are visible at the back of the skull, around the neck and around the front limbs.
Description
Pelecanimimus was a small ornithomimosaur, at about 2-2.5 m long (6.5 – 8 ft). Its skull was unusually long and narrow, with a maximum length of about 4.5 times its maximum height. It was highly unusual among ornithomimosaurs in its large number of teeth: it had about 220 very small teeth in total, with seven premaxillaPremaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry teeth, about thirty maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
ry, and seventy-five in the dentary. The teeth were heterodont
Heterodont
The anatomical term heterodont refers to animals which possess more than a single tooth morphology. For example, members of the Synapsida generally possess incisors, canines , premolars, and molars. The presence of heterodont dentition is evidence of some degree of feeding/hunting specialization...
, showing two different basic forms. The teeth in the front of the upper jaw were broad and D-shaped in cross-section, while those further back were blade-like, and on the whole the teeth in the upper jaw were larger than those in the lower. All of its teeth were unserrated, and had a constricted "waist" between the crown and the root. Interdental plates were lacking.
Only one other ornithomimosaur is known to possess teeth, Harpymimus
Harpymimus
Harpymimus is a basal ornithomimosaurian theropod dinosaur from the Early Cretaceous Period of what is now Mongolia. Unlike later, more derived ornithomimosaurs, Harpymimus still possessed teeth, although they appear to have been restricted to the dentary of the lower jaw.-Discovery and naming:In...
, which had far fewer (eleven total, and only in the lower jaw). The presence of such a large number of teeth in Pelecanimimus, coupled with a lack of interdental space, was interpreted by Pérez-Moreno et al. as an adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
for cutting and ripping, a "functional counterpart of the cutting edge of a beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
," as well as an exaptation
Exaptation
Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour...
leading to the toothless cutting edge found in later ornithomimosaurs.
The arms and hands of Pelecanimimus were more typical of ornithomimosaurs, with the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
bones in the lower arm tightly adhered to each other. The hand was hook-like and had fingers of equal length equipped with rather straight claws.
Soft-tissue remains preserved by the exceptional preservational environment of the La Hoyas lagerstätte revealed the presence of a small skin or keratin crest on the back of the head, and a gular pouch similar to the much larger pouches found in modern pelicans, from which Pelecanimimus took its name. Pelecanimimus might have been much like a modern day crane, wading out in lakes or ponds using its claws and teeth to capture fish and then storing them in its skin flap. Some parts of the impressions revealed wrinkled skin, interpreted as lacking scales or feathers. Filament-like structures were also preserved; first interpreted as an integument, these were later seen as representing preserved muscle fibers. Pelecanimimus was also the first ornithomimosaur discovered with a preserved hyoid apparatus (specialized tongue bones in the neck).
Phylogeny and evolution
Pelecanimimus was by the describers assigned to the Ornithomimosauria, in the basalmost position. A later cladistic analysis by Makovicky et al. (2005) confirmed that Pelecanimimus is the most basal member of the Ornithomimosauria, less derived even than Harpymimus. A study by Kobayashi and Lü in 2003 indicated that these two species formed a basal arrangement of steps leading towards the more advanced ornithomimids (see cladogram below). The discovery of Pelecanimimus has played an important and surprising role in understanding the evolutionEvolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
of the Ornithomimosauria. To quote Pérez-Moreno et al., "The phylogenetic hypothesis...supports an unexpected approach, involving exaptation, which might explain the evolutionary process towards the toothless condition in Ornithomimosauria. Until now, a progressive reduction in the number of teeth has been considered as the most likely explanation: the primitive tetanurine
Tetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
theropods have up to 80 teeth with tall blade-like crowns, and the primitive ornithomimosaurs have only a few small teeth. The phylogenetic hypothesis suggests an alternative evolutionary process based on a functional analysis of increasing numbers of teeth. A high number of teeth with enough interdental space and properly placed denticles (as in troodontids) would be an adaptation for cutting and ripping. On the other hand, an excessive number of teeth with no interdental space (as in Pelecanimimus) would be a functional counterpart of the cutting edge of a beak. Thus, increasing the number of teeth would be an adaptation for cutting and ripping, as long as the space between adjacent teeth was preserved...while it would have the effect of working as a beak if spaces were filled with more teeth. The adaption to a cut-and-rip function therefore becomes an exaptation with a slicing effect, eventually leading to the cutting edge seen in most ornithomimosaurs."
Cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
after Kobayashi and Lü, 2003:
Ornithomimosauria
|--Pelecanimimus
`--o--Harpymimus
Harpymimus
Harpymimus is a basal ornithomimosaurian theropod dinosaur from the Early Cretaceous Period of what is now Mongolia. Unlike later, more derived ornithomimosaurs, Harpymimus still possessed teeth, although they appear to have been restricted to the dentary of the lower jaw.-Discovery and naming:In...
`--o--Garudimimus
Garudimimus
Garudimimus is a basal ornithomimosaurian theropod dinosaur from the Upper Cretaceous of Mongolia.-Discovery and naming:...
`--Ornithomimidae
Paleobiology
The Las Hoyas lagerstätte has produced numerous other exquisitely preserved species, including the enantiornithineEnantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
birds Iberomesornis
Iberomesornis
Iberomesornis is a monotypic genus of enantiornithine bird of the Cretaceous of Spain.In 1985 the fossil of Iberomesornis was discovered by Armando Díaz Romeral in the Early Cretaceous Calizas de La Huérguina Formation at Las Hoyas, Cuenca Province, east central Spain, which dates to the late...
, Concornis
Concornis
Concornis was an enantiornithine bird. It lived during the Early Cretaceous, in the late Barremian stage or about 127-125 million years ago, and its remains are known from the Calizas de La Huérguina Formation at Las Hoyas, Cuenca province, Spain...
, and Eoalulavis
Eoalulavis
Eoalulavis was an enantiornithine bird. It lived during the Aptian in the Early Cretaceous, about 115 mya and is known from fossils found at Las Hoyas, Spain...
, along with non-avian
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
theropod teeth and a few fragmentary sauropod bones. Coarse sediments of the La Hoyas lagerstätte have produced bones of the ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
dinosaur Iguanodon
Iguanodon
Iguanodon is a genus of ornithopod dinosaur that lived roughly halfway between the first of the swift bipedal hypsilophodontids and the ornithopods' culmination in the duck-billed dinosaurs...
. The lagerstätte beds have also yielded remains of lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s and salamander
Salamander
Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant...
s.