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EXHIBIT 179

Dilong

Dilong paradoxus

Dilong was a small tyrannosauroid with long arms; a referred fossil preserves branching skin filaments. [2] [1]

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

Dilong paradoxus type IVPP V14243 skull displayed at the National Natural History Museum of China.

Dilong paradoxus holotype IVPP V14243 skull photographed by JonathanChen at the National Natural History Museum of China in July 2026. Flattening and visible display support are retained; the source provides no element-restoration key. This type-skull view does not show the filaments preserved in the separately referred, species-qualified V11579, or establish an adult whole-body outline. [1]

Dilong paradoxus holotype skull BMNHC.jpg · JonathanChen. CC BY 4.0. Current licensed Commons image converted to WebP and proportionally reduced for the thumbnail, without upsampling. No additional cropping, mirroring, anatomical edits or compositing. Existing source restoration and scale annotations retained. CC BY 4.0 applies to these versions.

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 Dilong paradoxus; missing anatomy, covering and colors are hypotheses.

Original cinematic interpretation of Dilong. Long three-fingered arms guide the restoration. Published Dilong material preserves filaments, although the assignment of the feather-bearing specimen to the named species was qualified; distribution and colors remain interpreted. 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.

PERIODEarly Cretaceous[1]
DIETCarnivoreEvidence and uncertainty in the dossier
TOTAL LENGTHSee the dossierEstimate scope matters
FOSSILS FOUNDChina[1]
CompareRead the dossierView the sources

MEET THE ANIMAL

Meet Dilong

Dilong was a small predatory relative of tyrannosaurs from Early Cretaceous China. Its fossils are important to discussions of featherlike coverings in the tyrannosaur family tree. The museum exhibition interprets simple filaments as possible insulation. That is a proposed function for the covering, rather than evidence of a particular temperature tolerance, seasonal coat or courtship display. [D2]

Filaments occur on a separately referred fossil that may represent a second Dilong species. They do not establish identical plumage on every individual. [D1]

A simple filament differs from a fully developed flight feather. Its presence adds information about the animal's covering without demonstrating flight or revealing the colors of a complete living body. Insulation is a reasonable interpretation to investigate, but it should not turn into an invented display or an assumed mating signal. [D2]

Researchers also reconstructed the shape of its brain cavity, which differs from that of giant tyrannosaurids. An endocast is a model of the spaces inside the skull, not the preserved brain behaving in life. Differences in its shape can support anatomical comparisons without directly measuring intelligence, proving a hunting strategy or demonstrating communication within a social group. [D3]

PREHISTORIC ANIMAL DOSSIER

A life in profile.

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

The fossils combine a gracile predatory skeleton with evidence of simple feather-like covering. They do not establish uniform plumage, color or an adult maximum. [D2]

Profile scope: Genus — Dilong; D. paradoxus type IVPP V14243 separated from filament-bearing referred V11579, whose species identification was qualified originally. [D1]

Time
Early Cretaceous
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 1.6 m (type reconstruction)

IVPP V14243 was the largest specimen described originally; this growing individual is not an adult maximum. [D1] [D4]

Body mass

Inferred

About 10 kg (limb model)

IVPP V14243; estimated circumference, juvenile possibly approaching maturity. [D4]

Diet and feeding

Inferred

Small predatory tyrannosauroid

Toothed anatomy supports carnivory. Cranial modelling compares possible feeding performance, rather than establishing prey choice or hunting tactics. [D2] [D5]

Habitat and setting

Source supported

Yixian Formation, Liaoning

Type locality Lujiatun and referred Zhangjiagou material lie in northeastern China’s Early Cretaceous fossil record; different specimens retain separate locality and species scope. [D1]

Movement

Inferred

Biped with long forelimbs

The gracile skeleton and three-fingered hand support terrestrial movement and grasping capacity. Exact speed and use of the hand remain inferred. [D1]

Recognizable anatomy

Source supported

Low cranial ridge; branching filaments

V11579 preserves jaw and tail filaments, with species referral uncertain. Full-body feather coverage and color are unestablished. [D1]

Reproduction & life together

Reproduction and nesting

Not established

Not established here

The type’s juvenile model designation does not establish sexual maturity. No inspected Dilong eggs, nests or parent–young association were found. [D4]

Mating and courtship

Not established

Not established here

Filaments may have provided insulation. The exhibition interpretation does not demonstrate display feathers, sex differences or mating behavior. [D2]

Social behavior

Not established

Not established here

An endocast reconstructs spaces within the skull, not social behavior. The reviewed brain study supplies no observed communication, group or family evidence. [D3]

Dossier research & sources

Sources and inspection notes for the claims in this profile.

  1. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids (Xu et al., 2004)Nature · Accessed 2026-10-02Original five-page article fully inspected in the IVPP-hosted PDF; supporting information was not included. Type IVPP V14243 approximately 1.6 m; Lujiatun, Yixian Formation, Liaoning. Filaments on lower jaw and tail of V11579, which may represent a second closely related Dilong species. Historical numerical formation ages are not adopted. Three-fingered manus and low Y-shaped cranial ridge. · Inspected: page
  2. A feathered tyrant (American Museum of Natural History)American Museum of Natural History · Accessed 2026-10-02Full institutional exhibition page inspected. Predatory tyrannosaur relative; simple filaments interpreted as possible insulation. The original paper’s qualified species referral is retained rather than collapsed into confirmed D. paradoxus plumage. · Inspected: page
  3. Evolutionary disparity in the endoneurocranial configuration between small and gigantic tyrannosauroids (Kundrát et al., online 2018; issue 2020)Historical Biology · Accessed 2026-10-02Original abstract inspected, not full paper. Dilong endocast is S-shaped, with forebrain overlapping middle/hindbrain; brain regions and venous sinuses differ from giant tyrannosaurids. Endocast comparison is not a direct behavior or intelligence measurement. · Inspected: abstract
  4. 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: IVPP V14243, estimated femoral circumference from published diameter, 10.085 kg. Juvenile flag 1; notes it may be approaching maturity, which does not establish adulthood. · Inspected: page
  5. Comparative cranial biomechanics reveal that Late Cretaceous tyrannosaurids exerted relatively greater bite force than in early-diverging tyrannosauroids (Johnson-Ransom et al., online 2023; issue 2024)The Anatomical Record · Accessed 2026-10-02Original full abstract, modelling methods and Table 1 inspected. Proceratosaurus NHM R 4860 and Dilong IVPP V14243 skulls were digitally sculpted and analyzed; internal cavities were omitted. These are conditional biomechanical models, not observed bites or direct measurements of living animals. · Inspected: page

THE STORY IN THE FOSSILS

Different fossils answer different questions.

The filament-bearing fossil and the measured type are separate specimens. Their evidence should not silently become a single fully preserved adult animal. [1]

A reconstructed brain cavity provides another comparison with giant tyrannosauroids. Differences in brain shape do not document a specific hunting strategy or social life. [3]

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. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids (Xu et al., 2004)Nature · Accessed 2026-10-02Original five-page article fully inspected in the IVPP-hosted PDF; supporting information was not included. Type IVPP V14243 approximately 1.6 m; Lujiatun, Yixian Formation, Liaoning. Filaments on lower jaw and tail of V11579, which may represent a second closely related Dilong species. Historical numerical formation ages are not adopted. Three-fingered manus and low Y-shaped cranial ridge. · Inspected: page
  2. A feathered tyrant (American Museum of Natural History)American Museum of Natural History · Accessed 2026-10-02Full institutional exhibition page inspected. Predatory tyrannosaur relative; simple filaments interpreted as possible insulation. The original paper’s qualified species referral is retained rather than collapsed into confirmed D. paradoxus plumage. · Inspected: page
  3. Evolutionary disparity in the endoneurocranial configuration between small and gigantic tyrannosauroids (Kundrát et al., online 2018; issue 2020)Historical Biology · Accessed 2026-10-02Original abstract inspected, not full paper. Dilong endocast is S-shaped, with forebrain overlapping middle/hindbrain; brain regions and venous sinuses differ from giant tyrannosaurids. Endocast comparison is not a direct behavior or intelligence measurement. · Inspected: abstract
  4. 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: IVPP V14243, estimated femoral circumference from published diameter, 10.085 kg. Juvenile flag 1; notes it may be approaching maturity, which does not establish adulthood. · Inspected: page
  5. Comparative cranial biomechanics reveal that Late Cretaceous tyrannosaurids exerted relatively greater bite force than in early-diverging tyrannosauroids (Johnson-Ransom et al., online 2023; issue 2024)The Anatomical Record · Accessed 2026-10-02Original full abstract, modelling methods and Table 1 inspected. Proceratosaurus NHM R 4860 and Dilong IVPP V14243 skulls were digitally sculpted and analyzed; internal cavities were omitted. These are conditional biomechanical models, not observed bites or direct measurements of living animals. · Inspected: page

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