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EXHIBIT 163

Limusaurus

Limusaurus inextricabilis

Limusaurus lost its teeth as it grew, transforming toothed young jaws into the beak of older animals. [2]

Evidence profile

TWO WAYS TO PICTURE THE PAST

Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.

01 / FOSSIL VIEW

The evidence in the bones

Annotated Limusaurus slab with type skeleton in green, gastroliths in red, a referred skeleton in blue and a crocodyliform in purple.

Limusaurus fossil slab photographed by ★Kumiko★, with existing Commons annotations by FunkMonk. Green marks L. inextricabilis type IVPP V15923, independently classified as subadult; red marks gastroliths, blue another referred skeleton and purple a crocodyliform. The diagram’s color overlays are identification aids, not living skin colors. This association is neither one complete animal nor demonstrated nesting evidence. [1]

Limusaurus slab colour coded.jpg · ★Kumiko★; existing annotations by FunkMonk. CC BY-SA 2.0. Current Commons 1280 px preview converted to WebP, with a proportionally reduced thumbnail; existing color annotations retained. No additional cropping, mirroring, anatomical edits or compositing. Derivatives retain CC BY-SA 2.0.

The photograph or figure shows the credited fossil material; displayed mounts and labels can include interpretation.

02 / MOVIE-STYLE INTERPRETATION

A cinematic imagination

Illustrative reconstruction of Limusaurus inextricabilis; missing anatomy, covering and colors are hypotheses.

Original cinematic interpretation of Limusaurus. This adult-stage toothless reconstruction differs from toothed juvenile fossils; fine skin, beak covering, colors and pose remain interpretive. Lighting, colors and scenery are artistic choices; this image does not document directly observed behavior. Lighting, coloration and scenery are artistic choices. This image does not document a fossil locality or behavior.

Original artwork · artistic interpretation.

Scientific view: source-informed reconstruction, credited paleoart or specimen-based imagery. Movie-style view: Original artistic interpretation. Reconstructions involve uncertainty.

PERIODLate Jurassic[1]
DIETOmnivore / HerbivoreEvidence and uncertainty in the dossier
TOTAL LENGTHSee the dossierEstimate scope matters
FOSSILS FOUNDChina[1]
CompareRead the dossierView the sources

MEET THE ANIMAL

Meet Limusaurus

Limusaurus was a Late Jurassic dinosaur from Xinjiang, China, with long hindlimbs and unusually short forelimbs. Its hands were reduced, including a first hand ray that was only a stub of bone without finger segments. The skeleton supports a two-legged reconstruction, but its proportions alone do not give a reliable running speed or reveal every use of the arms. [D1]

A series of nineteen fossils documents a striking change during growth: young animals had teeth, while mature animals were toothless. Swallowed stones and chemical evidence helped researchers propose a dietary shift from mixed feeding toward plant eating. That interpretation concerns changing feeding abilities. It does not identify a fixed menu, the exact prey eaten by youngsters or the plants preferred by adults. [D2]

Older jaws still contained enclosed traces of tooth sockets. These vestiges help explain how a toothless beak developed as tooth replacement stopped. The growing and older fossils are therefore not simply unrelated toothed and toothless dinosaurs. Their developmental differences provide evidence about changes during life, without independently identifying males and females or demonstrating a courtship display. [D3]

PREHISTORIC ANIMAL DOSSIER

A life in profile.

The animal, the evidence, and the questions still open.

Nineteen fossils record a changing anatomy and inferred diet. Several death pits preserve animals trapped successively rather than a demonstrated nesting colony. [D2] [D4]

Profile scope: Genus — Limusaurus; profile centered on L. inextricabilis, with juvenile, subadult and adult evidence distinguished. [D1] [D3]

Time
Late Jurassic
Fossil locations in this exhibit
China
How to read the evidence

Source supported identifies a description documented by the cited source. Inferred marks a reconstruction or functional estimate. Debated marks competing interpretations. Not established means the sources reviewed for this dossier do not support a firm conclusion; it does not mean a behavior never occurred.

A size reference is an estimate, not a population range. Nesting evidence does not by itself establish courtship, mate choice, or lifelong pairing.

Body length

Inferred

About 1.7 m (comparative reference)

Published comparison without specimen or maturity scope; not a mature maximum or measured species range. [D5]

Body mass

Inferred

About 17 kg (limb model)

IVPP V15923; estimated femoral circumference. Type independently identified as subadult. [D6] [D3]

Diet and feeding

Inferred

Inferred omnivory shifting to herbivory

Tooth loss, gastroliths and isotopic evidence support a dietary shift with growth; no specific plants or prey are securely identified. [D2]

Habitat and setting

Source supported

Shishugou seasonal alluvial setting

Oxfordian Wucaiwan, Xinjiang, China. Regional deposits include channels, wetlands and shallow lakes in a warm, seasonally dry landscape. [D1] [D4]

Movement

Inferred

Two-legged, with long hindlimbs

The skeleton has short forelimbs and comparatively long legs; these proportions do not establish a measured running speed. [D1]

Recognizable anatomy

Source supported

Growing tooth loss; short, reduced hands

The first manual ray is a metacarpal stub without phalanges. Older jaws are toothless; juvenile jaws retain teeth. [D1] [D3]

Reproduction & life together

Reproduction and nesting

Not established

Not established here

A six-stage growth series includes hatchlings and older animals. This documents development, not a nest, breeding age or parental behavior. [D2]

Mating and courtship

Not established

Not established here

Growth-related tooth loss does not establish sexual dimorphism, a mating display or a courtship sequence. [D3]

Social behavior

Inferred

Possible gregarious population, unconfirmed

The death-pit study proposed local gregariousness. Sequential trapping of many small animals does not demonstrate a single traveling herd or family group. [D4]

Dossier research & sources

Sources and inspection notes for the claims in this profile.

  1. A Jurassic ceratosaur from China helps clarify avian digital homologies (Xu et al., 2009)Nature; original paper hosted by Institute of Vertebrate Paleontology and Paleoanthropology · Accessed 2026-10-02Original anatomy, type and locality inspected: IVPP V15923 nearly complete articulated skeleton missing distal tail; short forelimbs, reduced metacarpal I without phalanges, toothless beak and gastroliths. Oxfordian Shishugou, Wucaiwan. Original V15924 adult inference is not transferred to the type. · Inspected: page
  2. Extreme ontogenetic changes in a ceratosaurian theropod (Wang et al., 2017; online 2016)Current Biology; PubMed original abstract · Accessed 2026-10-02Original abstract inspected: 19 specimens, six growth stages and 78 changes; young fully toothed, mature animals toothless. Gastroliths and stable isotopes support inferred dietary shift. Full paper was not accessible. · Inspected: abstract
  3. Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks (Wang et al., 2017)Proceedings of the National Academy of Sciences · Accessed 2026-10-02Original tooth-loss discussion and Fig. 1 inspected: V15923 explicitly identified as subadult; juvenile V15301 differs in dental development. Enclosed vestigial alveoli and shortened tooth replacement inform beak evolution, not breeding age. · Inspected: page
  4. Dinosaur death pits from the Jurassic of China (Eberth, Xing and Clark, 2010)PALAIOS · Accessed 2026-10-02Original abstract, depositional and discussion sections inspected: three pits, at least 15 Limusaurus individuals, successive miring and burial; sauropod-trampling liquefaction and possible gregarious local population are interpretations. Warm seasonally dry alluvial setting with wetlands. · Inspected: page
  5. Osteohistology and growth dynamics of the Brazilian noasaurid Vespersaurus paranaensis ... (de Souza et al., 2020)PeerJ · Accessed 2026-10-02Indexed original introduction and Fig. 1 excerpt inspected: approximately 1.7 m comparative reference for Limusaurus, not a new individual measurement or a maturity assessment. Full PDF fetch returned forbidden. · Inspected: excerpt
  6. Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage (Benson et al., 2014), Dataset S1PLOS Biology · Accessed 2026-10-02Original XLS inspected: V15923, estimated femoral circumference based on diameters/proportions, mass 17.19227 kg. Independent PNAS 2017 figure identifies this type as subadult. · Inspected: page

THE STORY IN THE FOSSILS

A beak acquired during growth.

Vestigial tooth sockets remain enclosed in older jaws. The growth series supports cessation of tooth replacement rather than a fossil sample of unrelated toothed and toothless species. [3]

Mud-pit carcasses accumulated successively. Their striking association records trapping and burial, while reproductive and social explanations need additional evidence. [4]

A note on scale and time

The dossier identifies the scope of each reference estimate. A mount, an individual fossil and a species-wide adult range are different measurements. Comparison metrics remain unavailable where adult scope has not been established. Unknown does not mean zero.

Sources & editorial notes

Sources support the stated claims and scopes. Refer to the evidence notes for uncertainty.

  1. A Jurassic ceratosaur from China helps clarify avian digital homologies (Xu et al., 2009)Nature; original paper hosted by Institute of Vertebrate Paleontology and Paleoanthropology · Accessed 2026-10-02Original anatomy, type and locality inspected: IVPP V15923 nearly complete articulated skeleton missing distal tail; short forelimbs, reduced metacarpal I without phalanges, toothless beak and gastroliths. Oxfordian Shishugou, Wucaiwan. Original V15924 adult inference is not transferred to the type. · Inspected: page
  2. Extreme ontogenetic changes in a ceratosaurian theropod (Wang et al., 2017; online 2016)Current Biology; PubMed original abstract · Accessed 2026-10-02Original abstract inspected: 19 specimens, six growth stages and 78 changes; young fully toothed, mature animals toothless. Gastroliths and stable isotopes support inferred dietary shift. Full paper was not accessible. · Inspected: abstract
  3. Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks (Wang et al., 2017)Proceedings of the National Academy of Sciences · Accessed 2026-10-02Original tooth-loss discussion and Fig. 1 inspected: V15923 explicitly identified as subadult; juvenile V15301 differs in dental development. Enclosed vestigial alveoli and shortened tooth replacement inform beak evolution, not breeding age. · Inspected: page
  4. Dinosaur death pits from the Jurassic of China (Eberth, Xing and Clark, 2010)PALAIOS · Accessed 2026-10-02Original abstract, depositional and discussion sections inspected: three pits, at least 15 Limusaurus individuals, successive miring and burial; sauropod-trampling liquefaction and possible gregarious local population are interpretations. Warm seasonally dry alluvial setting with wetlands. · Inspected: page
  5. Osteohistology and growth dynamics of the Brazilian noasaurid Vespersaurus paranaensis ... (de Souza et al., 2020)PeerJ · Accessed 2026-10-02Indexed original introduction and Fig. 1 excerpt inspected: approximately 1.7 m comparative reference for Limusaurus, not a new individual measurement or a maturity assessment. Full PDF fetch returned forbidden. · Inspected: excerpt
  6. Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage (Benson et al., 2014), Dataset S1PLOS Biology · Accessed 2026-10-02Original XLS inspected: V15923, estimated femoral circumference based on diameters/proportions, mass 17.19227 kg. Independent PNAS 2017 figure identifies this type as subadult. · Inspected: page

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