Published March 27, 2023. Open access.

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Crowned Dwarf Caiman (Paleosuchus trigonatus)

Reptiles of Ecuador | Crocodylia | Alligatoridae | Paleosuchus trigonatus

English common names: Crowned Dwarf Caiman, Schneider’s Dwarf Caiman, Smooth-fronted Caiman.

Spanish common names: Caimán corona, caimán yarina, caimán enano.

Recognition: ♂♂ 2.26 mMaximum distance from the snout to the tip of the tail. ♀♀ 1.33 mMaximum distance from the snout to the tip of the tail..1 The Crowned Dwarf Caiman (Paleosuchus trigonatus) is Ecuador’s smallest crocodilian.2 It can be distinguished from the other two caimans inhabiting the Ecuadorian Amazon (Caiman crocodilus and Melanosuchus niger) by being smaller, lacking a transverse preorbital ridge,1 and having strongly keeled scutes on the dorsum of the neck.3,4 The iris is deep chestnut brown and there is a blackish median stripe on the snout (Fig. 1).2 This species differs from its congener P. palpebrosus by having a longer, narrower snout,1 but the presence of the latter species has not been confirmed in Ecuador.5

Figure showing variation between individuals of Paleosuchus trigonatus

Figure 1: Individuals of Paleosuchus trigonatus from Yasuní Scientific Station, Orellana province, Ecuador (); Palmarí, Amazonas state, Brazil (); and Suchipakari Lodge, Napo province, Ecuador (). ad=adult, j=juvenile.

Natural history: Paleosuchus trigonatus is an uncommonUnlikely to be seen more than once every few months. to locally frequentRecorded weekly in densities below five individuals per locality. caiman in Amazonian Ecuador, with densities of up to ~1–3 caimans/km.6 Crowned Dwarf Caimans are nocturnal and aquatic, but more terrestrial than other caimans.7 They occur in small creeks, ponds, and swamps inside the rainforest,3,8,9 especially those that are too small for the other caiman species,1,4,7 but also marginally in pastures.10 They are present,11 but less common in larger water bodies such as lagoons and rivers, preferring more secluded habitats where they hide behind branches and fallen trees.1,12 During the day, they rest in the bottom among leaves, inside the mud, or hide in burrows below the water level.1 They can also spend days in terrestrial retreats such as inside hollow logs, in burrows built by the animals themselves, and beneath fallen trees up to 90 m from the water.13 The home range in males is up to 5 km2 and overlaps with that of several females.1,13 The diet in P. trigonatus includes crabs, shrimp, mollusks, spiders,10 scorpions,14 terrestrial insects, fish (including eels15), snakes (including Bothrops atrox and Corallus batesii15), amphibians (toads, including the toxic Rhinella marina,16 and caecilians17), mammals (including rats, agoutis, monkeys, marsupials, armadillos, and porcupines),18,19 and birds.18,20

Unlike other crocodilians, Crowned Dwarf Caimans are almost always found alone. Even juveniles start to disperse from the nest within a week from hatching.1,13 Females reach sexual maturity at around 11 years old or at a length of 1.3 m; males at 20 years old or at 1.4 m.13,20 Nesting in the Ecuadorian Amazon was registered in September, the rainiest month.21 Females wander upstream to the smallest creeks and build their nests 4.5–30 m from the bank1,7,13,21 and usually near termite mounds.22 The nests are 35–45 cm tall, mound-like, and built using leaf-litter, twigs, decaying vegetation, and soil.1,7,21,23 Clutches consist of 8–30 eggs that measure 6.5–6.8 cm in length, weigh ~74 g, and take ~90–100 days to hatch.7,2125 Temperature during incubation determines the sex of the hatchlings: nest temperatures over 31.5 °C produce mostly males and temperatures under 30.5 °C produce females.26 Females aggressively defend the nest from predators22 such as tegus (genus Tupinambis), armadillos, tayras, and coatis.22,23 Hatchlings measure ~23–25 cm in total length at birth20 and are capable of producing distress calls.27 Anacondas (Eunectes murinus) are the only known natural predators of adults.15

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..28 Paleosuchus trigonatus is listed in this category because the species is widely distributed, occurs in protected areas, and has large and stable populations.13,25 Furthermore, the heavily ossified skin of P. trigonatus is considered of little value in the pelt markets. Thus, the species has not been as widely exploited as other Amazonian caimans.25 The meat and eggs are consumed,1,11,20 but only on a subsistence basis.25

Distribution: Paleosuchus trigonatus is widely distributed throughout the Amazon basin and peripheral areas.25 In Ecuador, the species has been recorded at elevations between 147 and 589 m (Fig. 2).

Distribution of Paleosuchus trigonatus in Ecuador

Figure 2: Distribution of Paleosuchus trigonatus in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The name Paleosuchus is derived from the Greek words palaios (=ancient) and souchus (a crocodile).29 The specific epithet trigonatus, which is derived from the Greek words tres (=three) and gonia (=angle), probably refers to the prominent triangular dorsal scutes.30

See it in the wild: Although Smooth-fronted Caimans occur in forested streams throughout the Ecuadorian Amazon, logistically, they are easier to spot by navigating along rivers, particularly the Tiputini, Yasuní, and Cuyabeno rivers. These crocodilians are most easily found at night by detecting their bright orange eye-shine. However, in most areas, individuals are becoming increasingly wary of human presence,6 fleeing when approached.

Special thanks to Natasha K Clarke and Taline Kazandjian for symbolically adopting the Crowned Dwarf Caiman and helping bring the Reptiles of Ecuador book project to life.

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Acknowledgments: Special thanks to Christian Cave for finding one of the specimens of Paleosuchus trigonatus photographed in this account.

Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

Photographers: Jose Vieira,bAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador. Sebastián Di Doménico,dAffiliation: Keeping Nature, Bogotá, Colombia. Alejandro Arteaga,aAffiliation: Khamai Foundation, Quito, Ecuador. and Amanda QuezadabAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: Laboratorio de Herpetología, Universidad del Azuay, Cuenca, Ecuador.

How to cite? Arteaga A (2023) Crowned Dwarf Caiman (Paleosuchus trigonatus). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/HTJM5560

Literature cited:

  1. Medem FJ (1958) The crocodilian genus Paleosuchus. Fieldiana: Zoology 39: 227–247.
  2. Brazaitis P (1973) The identification of living crocodilians. Scientific Contributions of the New York Zoological Society 58: 59–101.
  3. Duellman WE (2005) Cusco amazónico: the lives of amphibians and reptiles in an Amazonian rainforest. Cornell University Press, Ithaca, 433 pp.
  4. Duellman WE (1978) The biology of an equatorial herpetofauna in Amazonian Ecuador. Publications of the Museum of Natural History, University of Kansas 65: 1–352.
  5. Ortiz DA, Ron SR (2013) En busca del caimán perdido: 35 años de estudios sobre caimanes en Ecuador. Nuestra Ciencia 15: 64–68.
  6. Ortiz Yépez DA (2012) Estudio poblacional de caimanes (Crocodylia: Alligatoridae) en la Amazonía Ecuatoriana. BSc thesis, Pontificia Universidad Católica del Ecuador, 87 pp.
  7. Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
  8. Magnusson WE (1985) Habitat selection, parasites and injuries in Amazonian crocodilians. Amazoniana 9: 193–204.
  9. Rebêlo GH, Lugli L (2001) Distribution and abundance of four caiman species (Crocodylia: Alligatoridae) in Jaú National Park, Amazonas, Brazil. Revista de Biología Tropical 49: 1096–1109.
  10. Campbell KE (1973) Habitat notes on Paleosuchus trigonatus (Schneider) in Peru. Journal of Herpetology 7: 318–320.
  11. De Souza-Mazurek RR (2001) Paleosuchus trigonatus (Scheider’s Smooth-fronted Caiman): habitat. Herpetological Review 32: 252.
  12. Brauer KD (2005) Distribución y uso de hábitat de Caiman crocodilus y Paleosuchus trigonatus en el Río Tiputini. BSc thesis, Universidad San Francisco de Quito, 55 pp.
  13. Magnusson WE, Lima AP (1991) The ecology of a cryptic predator, Paleosuchus trigonatus, in a tropical rainforest. Journal of Herpetology 25: 41–48.
  14. Morato SAA, Batista VBGV, Paz A (2011) Paleosuchus trigonatus (Smooth-fronted Caiman): diet and movement. Herpetological Bulletin 115: 34–35.
  15. Field notes, Reptiles of Ecuador book project.
  16. Barbosa de Assis V, Dos Santos T (2007) Paleosuchus trigonatus (Scheider’s Smooth-fronted Caiman): predation. Herpetological Review 38: 445.
  17. Sampaio PR, Da Silva MN, De Matos SA, De Matos LR, Acosta M (2013) First report of predation by a caiman (Paleosuchus trigonatus, Crocodylia: Alligatoridae) on a caecilian (Caecilia marcusi, Gymnophiona: Caecilidade). Salamandra 49: 227–228.
  18. Magnusson WE, da Silva EV, Lima AP (1987) Diets of Amazonian Crocodilians. Journal of Herpetology 21: 85–89.
  19. Ortiz DA, Betancourt R, Yánez- Muñoz MH (2013) Paleosuchus trigonatus (Schneider’s Smooth-fronted Caiman): diet. Herpetological Review 44: 135.
  20. Morales-Betancourt MA, Lasso CA, De La Ossa V J, Fajardo-Patiño A (2013) Biología y conservación de los Crocodylia de Colombia. Serie Editorial Recursos Hidrobiológicos y Pesqueros Continentales de Colombia, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt (IAvH), Bogotá, 335 pp.
  21. Rivas JA, Aktay SA, Owens RY (2001) Paleosuchus trigonatus (Schenider’s Smooth-fronted Caiman): nesting. Herpetological Review 32: 251.
  22. Campos Z, Muniz F, Magnusson WE (2016) Predation on eggs of Schneider’s dwarf caiman, Paleosuchus trigonatus (Schneider, 1807), by armadillos and other predators. Journal of Natural History 50: 1543 –1548.
  23. Valeris C, Perera-Romero L, Jasotao R, Asatali M, Castellanos H (2014) First record of Paleosuchus trigonatus (Crocodylia: Alligatoridae) nesting for Venezuela. Boletín de la Academia de Ciencias Físicas Matemáticas y Naturales de Venezuela 74: 9–14.
  24. Barão-Nóbrega JAL, Marioni B, Da Silveira R (2020) Paleosuchus trigonatus (Schneider’s Smooth-fronted Caiman): hatchling dispersal. Herpetological Review 51: 322–323.
  25. Ross JP (1998) Crocodiles: status survey and conservation action plan. IUCN/SSC Crocodile Specialist Group, Gainesville, 97 pp.
  26. Lang JW, Andrews HV (1994) Temperature-dependent sex determination in Crocodilians. The Journal of Experimental Zoology 270: 28–44.
  27. Marquis O, Mathevon N, Aubin T, Gaucher P, Lemaire J (2020) Observations on breeding site, bioacoustics and biometry of hatchlings of Paleosuchus trigonatus (Schneider, 1801) from the French Guiana (Crocodylia: Alligatoridae). Herpetology Notes 13: 513–516.
  28. Campos Z, Magnusson WE, Muniz F (2019) Paleosuchus trigonatus. The IUCN Red List of threatened species. Available from: DOI: 10.2305/IUCN.UK.2019- 1.RLTS.T46588A3010035.en
  29. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
  30. Magnusson WE (1992) Paleosuchus trigonatus (Schneider) Schneider’s Dwarf Caiman. Catalogue of American Amphibians and Reptiles 555: 1–3.

Appendix 1: Locality data used to create the distribution map of Paleosuchus trigonatus in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

ColombiaCaquetáBelén de AndaquíesiNaturalist; photo examined
ColombiaCaquetáCaserío Los ÁngelesSINCHI 894; Caicedo Portilla 2023
ColombiaCaquetáPuerto CaicedoMorales-Betancourt et al. 2013
ColombiaPutumayoKanakasGeopark Colombia et al. 2022
ColombiaPutumayoNariñoGeopark Colombia et al. 2022
ColombiaPutumayoRío GuamuésiNaturalist; photo examined
ColombiaPutumayoVereda Islas de CartagenaIAvH-R-9224; Borja-Acosta & Galeano Muñoz (2023)
EcuadorMorona SantiagoCusuimeOrtega-Andrade 2010
EcuadorMorona SantiagoMacumaiNaturalist; photo examined
EcuadorMorona SantiagoSawastianOrtega-Andrade 2010
EcuadorMorona SantiagoTaishaUjukam Kawarim 2015
EcuadorNapoColonia BolívariNaturalist; photo examined
EcuadorNapoFinca LizaiNaturalist; photo examined
EcuadorNapoJatun Sacha Biological StationFMNH 2012
EcuadorNapoLiana LodgeiNaturalist; photo examined
EcuadorNapoMisahuallíiNaturalist; photo examined
EcuadorNapoPuerto Napo, 4 km E ofiNaturalist; photo examined
EcuadorNapoReserva Forestal ApayacuPhoto by Axel Marchelie
EcuadorNapoReserve of Liana LodgeiNaturalist; photo examined
EcuadorNapoRío MisahuallíiNaturalist; photo examined
EcuadorNapoSan Vicente de los RíosiNaturalist; photo examined
EcuadorNapoSinchi SachaPhoto by Ernesto Arbeláez
EcuadorNapoSuchipakari LodgeThis work; Fig. 1
EcuadorNapoYachana LodgeReptiles of Ecuador book database
EcuadorNapoYachana ReserveWhitworth & Beirne 2011
EcuadorOrellanaAncayacuiNaturalist; photo examined
EcuadorOrellanaBetween Boyopare and DicaroiNaturalist; photo examined
EcuadorOrellanaBloque 31Libro PetroAmazonas
EcuadorOrellanaBodega NPWReptiles of Ecuador book database
EcuadorOrellanaCampo ITTiNaturalist; photo examined
EcuadorOrellanaCaño Aguas Negras 1Ortiz 2012
EcuadorOrellanaCaño Aguas Negras 2Ortiz 2012
EcuadorOrellanaCaño BogiOrtiz 2012
EcuadorOrellanaCaño PirañaOrtiz 2012
EcuadorOrellanaEl CuraiNaturalist; photo examined
EcuadorOrellanaEl Eden Amazon LodgeiNaturalist; photo examined
EcuadorOrellanaEl RefugioiNaturalist; photo examined
EcuadorOrellanaHuaticochaMCZ 84029; VertNet
EcuadorOrellanaKawymeno, 2 km W ofiNaturalist; photo examined
EcuadorOrellanaLaguna JatuncochaiNaturalist; photo examined
EcuadorOrellanaMandaripanga campo, 12 km E ofiNaturalist; photo examined
EcuadorOrellanaNapo Wildlife CenteriNaturalist; photo examined
EcuadorOrellanaNPFPhoto by Paulina Romero
EcuadorOrellanaNuevo RocafuertePhoto by Paolo Escobar
EcuadorOrellanaPaushiyacuKingsbury et al. 2008
EcuadorOrellanaPozo EdéniNaturalist; photo examined
EcuadorOrellanaRío Aguarico along peruvian borderiNaturalist; photo examined
EcuadorOrellanaRío CononacoiNaturalist; photo examined
EcuadorOrellanaRío PayaminoiNaturalist; photo examined
EcuadorOrellanaRío ShiripunoiNaturalist; photo examined
EcuadorOrellanaRío Tiputini, near YCSReptiles of Ecuador book database
EcuadorOrellanaSan José de PayaminoMaynard et al. 2016
EcuadorOrellanaSan Sebastián del CocaiNaturalist; photo examined
EcuadorOrellanaShiripuno LodgePhoto by Fernando Vaca
EcuadorOrellanaTio YacuiNaturalist; photo examined
EcuadorOrellanaTiputini Biodiversity Station Dammer Brauer 2005
EcuadorOrellanaVía MaxusiNaturalist; photo examined
EcuadorOrellanaYarina LodgeiNaturalist; photo examined
EcuadorOrellanaYasuní Scientific StationReptiles of Ecuador book database
EcuadorPastazaAndoasAMNH 61548; VertNet
EcuadorPastazaAnga CochaAMNH 72470
EcuadorPastazaArajunoiNaturalist; photo examined
EcuadorPastazaArajuno, alrededoresiNaturalist; photo examined
EcuadorPastazaBalsauraOrtega-Andrade 2010
EcuadorPastazaBamenoiNaturalist; photo examined
EcuadorPastazaConamboOrtega-Andrade 2010
EcuadorPastazaJuyuintzaOrtega-Andrade 2010
EcuadorPastazaKapawi LodgeReptiles of Ecuador book database
EcuadorPastazaKurintzaOrtega-Andrade 2010
EcuadorPastazaPindoyacuOrtega-Andrade 2010
EcuadorPastazaRío NushiñoiNaturalist; photo examined
EcuadorPastazaRío PindoUSNM 196271; VertNet
EcuadorPastazaRío VillanoiNaturalist; photo examined
EcuadorPastazaSarayacuUSNM 211267; VertNet
EcuadorSucumbíosBloque 60iNaturalist; photo examined
EcuadorSucumbíosCabenoiNaturalist; photo examined
EcuadorSucumbíosCampo PlatanilloEnvirotec 2015
EcuadorSucumbíosCaño CuyabenoOrtiz 2012
EcuadorSucumbíosCaño PañacochaiNaturalist; photo examined
EcuadorSucumbíosCaño YarinaOrtiz 2012
EcuadorSucumbíosComunidad ZábaloCevallos Bustos 2010
EcuadorSucumbíosDurenoYánez-Muñoz & Chimbo 2007
EcuadorSucumbíosGüeppicilloYánez-Muñoz & Venegas 2008
EcuadorSucumbíosLago Agrio, 10 km NE ofiNaturalist; photo examined
EcuadorSucumbíosLaguna GrandeiNaturalist; photo examined
EcuadorSucumbíosLaguna TaracoaiNaturalist; photo examined
EcuadorSucumbíosLos OlivosiNaturalist; photo examined
EcuadorSucumbíosLumbaquiiNaturalist; photo examined
EcuadorSucumbíosPalmeras NorteiNaturalist; photo examined
EcuadorSucumbíosParque Ecologico Nueva LojaReptiles of Ecuador book database
EcuadorSucumbíosPetroamazonas campReptiles of Ecuador book database
EcuadorSucumbíosPlayas del Cuyabeno, nearbyOrtiz et al. 2013
EcuadorSucumbíosPuente Río Cuyabeno, 3 km W ofiNaturalist; photo examined
EcuadorSucumbíosPuerto El CarmeniNaturalist; photo examined
EcuadorSucumbíosReserva Biológica LimoncochaReptiles of Ecuador book database
EcuadorSucumbíosReserva CuyabenoiNaturalist; photo examined
EcuadorSucumbíosRío ChamangaiNaturalist; photo examined
EcuadorSucumbíosRío Cuyabeno, near Tapir LodgeiNaturalist; photo examined
EcuadorSucumbíosRío GüeppiYanez-Muñoz et al. 2017
EcuadorSucumbíosRío LagartocochaOrtiz & Ron 2013
EcuadorSucumbíosRío ZábaloiNaturalist; photo examined
EcuadorSucumbíosSacha LodgeiNaturalist; photo examined
EcuadorSucumbíosSan RoqueiNaturalist; photo examined
EcuadorSucumbíosSanta Cecilia Duellman 1978
EcuadorSucumbíosTarapoaiNaturalist; photo examined
PeruAmazonasQuebrada KampankisFMNH 2012
PeruAmazonasRío KagkaUSNM 317556; VertNet
PeruAmazonasRío KayamasUSNM 317554; VertNet
PeruAmazonasShaimUSNM 317555; VertNet
PeruAmazonasWayapUSNM 316913; VertNet
PeruLoretoAllpahuayo-Mishana National ReservePhoto by Roel de Plecker
PeruLoretoCampo AndoasValqui Schult 2015
PeruLoretoMoroponTCWC 41812; VertNet
PeruLoretoPongo ChinimFMNH 2012
PeruLoretoReserva Nacional PucacuroGómez Vásquez 2015
PeruLoretoRío Cononaco in PeruiNaturalist; photo examined