Published March 27, 2023. Open access. | Gallery ❯ |
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 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.7,21–25 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
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).
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.
Click here to adopt a species.
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: www.reptilesofecuador.com. DOI: 10.47051/HTJM5560
Literature cited:
- Medem FJ (1958) The crocodilian genus Paleosuchus. Fieldiana: Zoology 39: 227–247.
- Brazaitis P (1973) The identification of living crocodilians. Scientific Contributions of the New York Zoological Society 58: 59–101.
- Duellman WE (2005) Cusco amazónico: the lives of amphibians and reptiles in an Amazonian rainforest. Cornell University Press, Ithaca, 433 pp.
- 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.
- Ortiz DA, Ron SR (2013) En busca del caimán perdido: 35 años de estudios sobre caimanes en Ecuador. Nuestra Ciencia 15: 64–68.
- Ortiz Yépez DA (2012) Estudio poblacional de caimanes (Crocodylia: Alligatoridae) en la Amazonía Ecuatoriana. BSc thesis, Pontificia Universidad Católica del Ecuador, 87 pp.
- Dixon JR, Soini P (1986) The reptiles of the upper Amazon Basin, Iquitos region, Peru. Milwaukee Public Museum, Milwaukee, 154 pp.
- Magnusson WE (1985) Habitat selection, parasites and injuries in Amazonian crocodilians. Amazoniana 9: 193–204.
- 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.
- Campbell KE (1973) Habitat notes on Paleosuchus trigonatus (Schneider) in Peru. Journal of Herpetology 7: 318–320.
- De Souza-Mazurek RR (2001) Paleosuchus trigonatus (Scheider’s Smooth-fronted Caiman): habitat. Herpetological Review 32: 252.
- 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.
- Magnusson WE, Lima AP (1991) The ecology of a cryptic predator, Paleosuchus trigonatus, in a tropical rainforest. Journal of Herpetology 25: 41–48.
- Morato SAA, Batista VBGV, Paz A (2011) Paleosuchus trigonatus (Smooth-fronted Caiman): diet and movement. Herpetological Bulletin 115: 34–35.
- Field notes, Reptiles of Ecuador book project.
- Barbosa de Assis V, Dos Santos T (2007) Paleosuchus trigonatus (Scheider’s Smooth-fronted Caiman): predation. Herpetological Review 38: 445.
- 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.
- Magnusson WE, da Silva EV, Lima AP (1987) Diets of Amazonian Crocodilians. Journal of Herpetology 21: 85–89.
- Ortiz DA, Betancourt R, Yánez- Muñoz MH (2013) Paleosuchus trigonatus (Schneider’s Smooth-fronted Caiman): diet. Herpetological Review 44: 135.
- 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.
- Rivas JA, Aktay SA, Owens RY (2001) Paleosuchus trigonatus (Schenider’s Smooth-fronted Caiman): nesting. Herpetological Review 32: 251.
- 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.
- 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.
- Barão-Nóbrega JAL, Marioni B, Da Silveira R (2020) Paleosuchus trigonatus (Schneider’s Smooth-fronted Caiman): hatchling dispersal. Herpetological Review 51: 322–323.
- Ross JP (1998) Crocodiles: status survey and conservation action plan. IUCN/SSC Crocodile Specialist Group, Gainesville, 97 pp.
- Lang JW, Andrews HV (1994) Temperature-dependent sex determination in Crocodilians. The Journal of Experimental Zoology 270: 28–44.
- 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.
- Campos Z, Magnusson WE, Muniz F (2019) Paleosuchus trigonatus. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019- 1.RLTS.T46588A3010035.en
- Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
- 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.
| Country | Province | Locality | Source |
| Colombia | Caquetá | Belén de Andaquíes | iNaturalist; photo examined |
| Colombia | Caquetá | Caserío Los Ángeles | SINCHI 894; Caicedo Portilla 2023 |
| Colombia | Caquetá | Puerto Caicedo | Morales-Betancourt et al. 2013 |
| Colombia | Putumayo | Kanakas | Geopark Colombia et al. 2022 |
| Colombia | Putumayo | Nariño | Geopark Colombia et al. 2022 |
| Colombia | Putumayo | Río Guamués | iNaturalist; photo examined |
| Colombia | Putumayo | Vereda Islas de Cartagena | IAvH-R-9224; Borja-Acosta & Galeano Muñoz (2023) |
| Ecuador | Morona Santiago | Cusuime | Ortega-Andrade 2010 |
| Ecuador | Morona Santiago | Macuma | iNaturalist; photo examined |
| Ecuador | Morona Santiago | Sawastian | Ortega-Andrade 2010 |
| Ecuador | Morona Santiago | Taisha | Ujukam Kawarim 2015 |
| Ecuador | Napo | Colonia Bolívar | iNaturalist; photo examined |
| Ecuador | Napo | Finca Liza | iNaturalist; photo examined |
| Ecuador | Napo | Jatun Sacha Biological Station | FMNH 2012 |
| Ecuador | Napo | Liana Lodge | iNaturalist; photo examined |
| Ecuador | Napo | Misahuallí | iNaturalist; photo examined |
| Ecuador | Napo | Puerto Napo, 4 km E of | iNaturalist; photo examined |
| Ecuador | Napo | Reserva Forestal Apayacu | Photo by Axel Marchelie |
| Ecuador | Napo | Reserve of Liana Lodge | iNaturalist; photo examined |
| Ecuador | Napo | Río Misahuallí | iNaturalist; photo examined |
| Ecuador | Napo | San Vicente de los Ríos | iNaturalist; photo examined |
| Ecuador | Napo | Sinchi Sacha | Photo by Ernesto Arbeláez |
| Ecuador | Napo | Suchipakari Lodge | This work; Fig. 1 |
| Ecuador | Napo | Yachana Lodge | Reptiles of Ecuador book database |
| Ecuador | Napo | Yachana Reserve | Whitworth & Beirne 2011 |
| Ecuador | Orellana | Ancayacu | iNaturalist; photo examined |
| Ecuador | Orellana | Between Boyopare and Dicaro | iNaturalist; photo examined |
| Ecuador | Orellana | Bloque 31 | Libro PetroAmazonas |
| Ecuador | Orellana | Bodega NPW | Reptiles of Ecuador book database |
| Ecuador | Orellana | Campo ITT | iNaturalist; photo examined |
| Ecuador | Orellana | Caño Aguas Negras 1 | Ortiz 2012 |
| Ecuador | Orellana | Caño Aguas Negras 2 | Ortiz 2012 |
| Ecuador | Orellana | Caño Bogi | Ortiz 2012 |
| Ecuador | Orellana | Caño Piraña | Ortiz 2012 |
| Ecuador | Orellana | El Cura | iNaturalist; photo examined |
| Ecuador | Orellana | El Eden Amazon Lodge | iNaturalist; photo examined |
| Ecuador | Orellana | El Refugio | iNaturalist; photo examined |
| Ecuador | Orellana | Huaticocha | MCZ 84029; VertNet |
| Ecuador | Orellana | Kawymeno, 2 km W of | iNaturalist; photo examined |
| Ecuador | Orellana | Laguna Jatuncocha | iNaturalist; photo examined |
| Ecuador | Orellana | Mandaripanga campo, 12 km E of | iNaturalist; photo examined |
| Ecuador | Orellana | Napo Wildlife Center | iNaturalist; photo examined |
| Ecuador | Orellana | NPF | Photo by Paulina Romero |
| Ecuador | Orellana | Nuevo Rocafuerte | Photo by Paolo Escobar |
| Ecuador | Orellana | Paushiyacu | Kingsbury et al. 2008 |
| Ecuador | Orellana | Pozo Edén | iNaturalist; photo examined |
| Ecuador | Orellana | Río Aguarico along peruvian border | iNaturalist; photo examined |
| Ecuador | Orellana | Río Cononaco | iNaturalist; photo examined |
| Ecuador | Orellana | Río Payamino | iNaturalist; photo examined |
| Ecuador | Orellana | Río Shiripuno | iNaturalist; photo examined |
| Ecuador | Orellana | Río Tiputini, near YCS | Reptiles of Ecuador book database |
| Ecuador | Orellana | San José de Payamino | Maynard et al. 2016 |
| Ecuador | Orellana | San Sebastián del Coca | iNaturalist; photo examined |
| Ecuador | Orellana | Shiripuno Lodge | Photo by Fernando Vaca |
| Ecuador | Orellana | Tio Yacu | iNaturalist; photo examined |
| Ecuador | Orellana | Tiputini Biodiversity Station | Dammer Brauer 2005 |
| Ecuador | Orellana | Vía Maxus | iNaturalist; photo examined |
| Ecuador | Orellana | Yarina Lodge | iNaturalist; photo examined |
| Ecuador | Orellana | Yasuní Scientific Station | Reptiles of Ecuador book database |
| Ecuador | Pastaza | Andoas | AMNH 61548; VertNet |
| Ecuador | Pastaza | Anga Cocha | AMNH 72470 |
| Ecuador | Pastaza | Arajuno | iNaturalist; photo examined |
| Ecuador | Pastaza | Arajuno, alrededores | iNaturalist; photo examined |
| Ecuador | Pastaza | Balsaura | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Bameno | iNaturalist; photo examined |
| Ecuador | Pastaza | Conambo | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Juyuintza | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Kapawi Lodge | Reptiles of Ecuador book database |
| Ecuador | Pastaza | Kurintza | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Pindoyacu | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Río Nushiño | iNaturalist; photo examined |
| Ecuador | Pastaza | Río Pindo | USNM 196271; VertNet |
| Ecuador | Pastaza | Río Villano | iNaturalist; photo examined |
| Ecuador | Pastaza | Sarayacu | USNM 211267; VertNet |
| Ecuador | Sucumbíos | Bloque 60 | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Cabeno | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Campo Platanillo | Envirotec 2015 |
| Ecuador | Sucumbíos | Caño Cuyabeno | Ortiz 2012 |
| Ecuador | Sucumbíos | Caño Pañacocha | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Caño Yarina | Ortiz 2012 |
| Ecuador | Sucumbíos | Comunidad Zábalo | Cevallos Bustos 2010 |
| Ecuador | Sucumbíos | Dureno | Yánez-Muñoz & Chimbo 2007 |
| Ecuador | Sucumbíos | Güeppicillo | Yánez-Muñoz & Venegas 2008 |
| Ecuador | Sucumbíos | Lago Agrio, 10 km NE of | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Laguna Grande | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Laguna Taracoa | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Los Olivos | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Lumbaqui | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Palmeras Norte | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Parque Ecologico Nueva Loja | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Petroamazonas camp | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Playas del Cuyabeno, nearby | Ortiz et al. 2013 |
| Ecuador | Sucumbíos | Puente Río Cuyabeno, 3 km W of | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Puerto El Carmen | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Reserva Biológica Limoncocha | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Reserva Cuyabeno | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Río Chamanga | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Río Cuyabeno, near Tapir Lodge | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Río Güeppi | Yanez-Muñoz et al. 2017 |
| Ecuador | Sucumbíos | Río Lagartococha | Ortiz & Ron 2013 |
| Ecuador | Sucumbíos | Río Zábalo | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Sacha Lodge | iNaturalist; photo examined |
| Ecuador | Sucumbíos | San Roque | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Santa Cecilia | Duellman 1978 |
| Ecuador | Sucumbíos | Tarapoa | iNaturalist; photo examined |
| Peru | Amazonas | Quebrada Kampankis | FMNH 2012 |
| Peru | Amazonas | Río Kagka | USNM 317556; VertNet |
| Peru | Amazonas | Río Kayamas | USNM 317554; VertNet |
| Peru | Amazonas | Shaim | USNM 317555; VertNet |
| Peru | Amazonas | Wayap | USNM 316913; VertNet |
| Peru | Loreto | Allpahuayo-Mishana National Reserve | Photo by Roel de Plecker |
| Peru | Loreto | Campo Andoas | Valqui Schult 2015 |
| Peru | Loreto | Moropon | TCWC 41812; VertNet |
| Peru | Loreto | Pongo Chinim | FMNH 2012 |
| Peru | Loreto | Reserva Nacional Pucacuro | Gómez Vásquez 2015 |
| Peru | Loreto | Río Cononaco in Peru | iNaturalist; photo examined |